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Über dieses Buch

To sort out the progress of aviation science and technology and industry, look forward to the future development trend, commend scientific and technological innovation achievements and talents, strengthen international cooperation, promote discipline exchanges, encourage scientific and technological innovation, and promote the development of aviation, the Chinese Aeronautical Society holds a China Aviation Science and Technology Conference every two years, which has been successfully held for four times and has become the highest level, largest scale, most influential and authoritative science and technology conference in the field of aviation in China. The 5th China Aviation Science and Technology Conference will be held in Wuzhen, Jiaxing City, Zhejiang Province in 2021, with the theme of "New Generation of Aviation Equipment and Technology", with academician Zhang Yanzhong as the chairman of the conference.

This book contains original, peer-reviewed research papers from the conference. The topics covered include but are not limited to navigation, guidance and control technologies, key technologies for aircraft design and overall optimization, aviation test technologies, aviation airborne systems, electromechanical technologies, structural design, aerodynamics and flight mechanics, other related technologies, advanced aviation materials and manufacturing technologies, advanced aviation propulsion technologies, and civil aviation transportation. The papers presented here share the latest discoveries on aviation science and technology, making the book a valuable asset for researchers, engineers, and students.



Mechanical Modeling and Simulation for the Take-Off and Landing Performance Calculation of Low-Cost UAVs

Take-off and landing performance, which is supposed to satisfy high standard and always plays an important role during the whole lifespan of an aircraft, is necessary to be fully considered and systematically evaluated during the designing process. In this paper, aiming at determining the take-off and landing demands for low-cost UAVs, aero-dynamic analysis and mechanical modeling are launched to calculate the key parameters of related take-off and landing performance. According to different conditions of application, two theoretical models for take-off as well as two for landing process are established in detail, and an original method for correcting aerodynamic drag and fric-tion is proposed. The calculating methods for the time and distance during take-off and landing period are provided while simulation based on MATLAB is carried out to visually present the results. Based on the output of calculation and numerical analysis, the effectiveness and feasibility of the models are verified. The results indicate that the models proposed in this paper are efficient to estimate the take-off and landing performance of low-cost UAVs and also provide rapid and convenient support to carry out demands analysis and the design of low-cost UAVs especially in the preliminary phase.

Dai Yuke, Li Jun, Xu Yiming

Research on Dynamic Deformation Reconstruction Method of Full Size Wing Rocket Sled Based on Optical Fiber Strain

UAV usually has the characteristics of high aspect ratio, and its wings are easy to produce large deformation during flight, which threatens the flight safety of UAV. Although the large UAV wing can be used for wind tunnel test of scaled model, the scaled model will affect the wing stiffness. Using the rocket sled platform to measure the deformation of the full-scale wing at different angles of attack/sideslip under the real flow velocity, the 1:1 high aspect ratio wing strength test can be carried out. It is an ideal method to use k.o theory algorithm to reconstruct the wing deformation by distributing strain parameters and pasting optical fiber strain device on the wing surface, which makes use of the characteristics of thin core diameter and light weight of optical fiber sensor.

Ranzhong Yao, Hongcheng Zhou, Jipeng Liu

Strength Design and Research of Fuselage Opening Zone of Civil Aircraft

There are many cabin doors in the fuselage of civil aircraft, that can cause fuselage stiffness and transfer of load discontinuity. In order to keep structural integrity and transfer of load of aircraft, cutout of fuselage should be strengthened to hold and transmit the surrounding load. The compare between the opening fuselage and integrity fuselage are formulated through a theoretical analysis. The principle and the method to strengthen the fuselage with large opening are successfully applied on the aircraft in the preliminary design stage and can be used to guide the structure preliminary design.

Kaijun Yin, Yinli Zhang, Renjun Sun

Characterization of the Rate-Dependent Behavior of Phenyl Silicone Rubber

The model of rate-dependent mechanical behavior for the damping rubber material is proposed based on Petiteau’s time convolution integral model in terms of the K-BKZ model and Xiang’s constitutive model to characterize the hyperelastic response under various deformation states. Furthermore, the specimen of PVMQ with different Phenyl contents were prepared, and the mechanical behaviors of the samples were tested at various strain rates. Within a small stretch ratio, the materials are mainly characterized by elastic or hyperelastic behaviors rather than viscous behavior. When the material’s stretch beyond the elastic section, the viscous behavior gradually manifests itself and the materials are showing sensitivity to strain rates. With the increase of phenyl content in the materials, the influence of strain rate will be weakened. The model can characterize the mechanical behaviour of the damping materials accurately under various strain rates. In addition, this viscoelastic model could be used to predict the mechanical response of Phenyl silicone rubber in the dynamic mechanical environments.

Yuxing Duan, Xulong Xi, Yunfeng Zhao, Zhijie Zhang

Design and Realization of Robotic Automatic Drilling & Riveting Controlling System for Single-Sided Fasteners

This paper presents a robotic automatic drilling and riveting system for single-sided fasteners composed of a robot, an end effector including an intelligent camera and normal measurement cells, a rivet feeder, and some auxiliary system. The control system is designed with the functions of normal adjustment, drilling and riveting position adjustment, compaction, drilling, rivets feeding, glue spread, workstation conversion, and riveting. In order to meet the design needs, communication networks including EtherCAT bus, TCP/IP, serial communication, Automation Device Specification (ADS) communication, and digital IO communication are implemented. The laser sensors and intelligent camera assist to realize algorithms of the normal adjustment and the drilling and riveting positioning. The drilling and riveting system is verified by experiments of flat plate and curved surface. At last, a conclusion is made based on the experiment results which show drilling accuracy the maxi-mum aperture accuracy is 0.016 mm, the maximum deviation of dimple depth is 0.025 mm and the maximum deviation of normal is 0.151°. Aperture accuracy can reach H9 and the efficiency of drilling and riveting in this system can be 5/min.

Jiangkun Shang, Guanyu Cao, Yingchao Zhai, Feiyana Guo, Qingdong Xiao, Lu Gan, Zhan Li

Experimental Study of Temperature on Eddy Current Sensor for Clearance Measurement

High-precision eddy current sensors are mainly used for measuring the tip clearance of rotating parts of aero-engines in which the ambient temperature is up to 2000 K. The coil impedance value of the eddy current sensor not only reflects the distance from the probe to the conductor, it is also affected by the ambient temperature. Thus, it is necessary to investigate the influence of temperature on the eddy current sensor probe. The experimental research show: when the temperature is lower than 673 K, the temperature has a significant effect on the eddy current sensor gap measurement curve. Otherwise, it’s not. Secondly, it is found that when the ambient temperature is between 573 K and 1273 K, the equivalent resistance of the eddy current sensor increases linearly with temperature, with an average change of 60%, but the average change of its equivalent inductance with temperature is only 5%. In addition, the experimental results also prove that the leaf tip gap eddy current sensor can be used not only to measure the gap, but also to measure the ambient temperature. The eddy current sensor can be used as a multifunction sensor in the engineering application with the corresponding data processing method.

Lingqiang Zhao, Yaguo Lyu, Zhenxia Liu, Yuhao Zhou

Numerical Investigation of Riblets on Rod-Airfoil Interaction Noise

Turbulence interaction noise is widely present in the aviation field. In order to adapt the increasingly stringent airworthiness noise standards, new noise reduction measures must be explored to break through the noise reduction bottleneck. The large eddy simulation and FW-H equation were used to study the influences of three riblets on the rod-airfoil interaction noise. The riblet reduces the wall shear stress on the surface of the rod, delays the flow separation of the boundary layer, and breaks the large-scale vortex structure after the rod has fallen off into small-scale vortex structures, thereby reducing RMS velocity and spanwise vorticity intensity of the wake. The stability of the downstream airfoil and the surrounding flow field is improved, and RMS pressure fluctuation is reduced, thus the interaction noise of the rod-airfoil is decreased. D15 can drop the tonal noise of rod by 21.35 dB and airfoil noise by 10.57 dB.

Chenghao Yang, Heying Feng, Yehui Peng, Nvzi Bao

System Level Study of Light Sport Aircraft with Conventional and Unconventional Propulsion Systems

Unconventional propulsion systems, such as electric motors, fuel cells with propellers or ducted fans have been considered as significant enablers for reducing aviation carbon emissions. However, the power and energy magnitude required for transport aircraft and other large aircraft are beyond the capability of the state-of-the-art electric propulsion technologies. In this paper, the overall aircraft level study on both conventional and unconventional propulsion systems is carried out. Based on the in-house overall aircraft design framework, multi-disciplinary results of the baseline light sport aircraft are achieved. Through comprehensive sensitivity studies of different propulsion systems, system level comparison results have been obtained. As compared to the worst case, LSA with conventional propulsion systems can achieve more than 30% fuel burn reduction at best flight speed and flight altitude condition. The electric retrofit result has shown that promising fuel burn reduction (carbon emission reduction) can be achieved at the costs of significant flight range decrease, which might give some indications to the selection of propulsion systems for future light sport aircraft development.

Yaolong Liu, Jifa Zhang, Yao Zheng, Tianhong Jiang, Jiechao Zhang

Research on Robust Scheduling Method Based on Operation Interval Relaxation

Aircraft manufacturing companies have long production cycles and complex product structures. The assembly process involves a variety of parts and components. There are many types of materials and high requirements for complete sets. The delayed delivery of a certain material will produce a domino effect, which will cause the delivery time of the final parts to be delayed by multiples. In order to reduce the influence of operation delay on the scheduling scheme, this paper studies the robust scheduling operation time difference relaxation. Considering the effect of delay, the robust indexes are selected, and a robust scheduling model with uncertain delays in a single operation is constructed. Then, a robust scheduling method based on operation interval relaxation is proposed, the priority order of operation time difference relaxation is analyzed, and the position and size of the operation time difference relaxation is obtained. Finally, some experiments demonstrated the effectiveness of the operation time difference relaxation method.

Feng Deng, Shuo Chen, Hengyi Gao, Lin Qi, Bingsheng Wang

Research on Out-of-Plane Shear Mechanical Properties of Damaged Composite T-joints

Composite materials have been widely used in the aviation field because of their light weight, large modulus and high strength. In this paper, the interface mechanical properties of composite T-joints under shear load are tested through experiments, which concluded that the ultimate load of the structure with defects is reduced from 29.01 kN to 27.40 kN and its bearing capacity is reduced by 5.5%. Then, based on the Cohesive Zone Model (CZM), a progressive damage model is established for damage failure analysis. The results show that the damage under shear load mainly extends from both sides to the center. When there is a prefabricated defect in the interface layer, the initial damage occurs near the defect and spreads to both ends of the load direction.

Xuanjia Zhang, Heyuan Huang, Dong Wang

Hybrid Optimization of Arrival and Departure Flight Schedules

With the growth of air transport demand and the substantial increase of air transport volume, the airport flight schedule is becoming more and more intensive, even hard to find for a moment. As a result, some aircraft can not land or take off at the expected time. This paper studies the aircraft arrival scheduling problem in airports with multi-runways within the terminal area. It is different from the previous studies, according to the terminal area air traffic control operation rules, and this paper takes minimizing the total flight delay as the goal, considers the constraints of arrival point, flight schedule adjustment range, take-off interval and runway occupation time, establishes the flight schedule optimization model, and uses permutation coding method to solve the model using genetic algorithm. The results show that the proposed method can reduce the delay by 31.03% and improve the flight punctuality rate.

Jingxian Li, Qi Zhong, Liu Yi, Qiang Wang, Jiejun Zuo, Yong Liu

Research and Application of Simulation Technology in Airspace Capacity Assessment

With the continuous increasement of flights, the airspace becomes more and more crowded. The airspace capacity has become a research hot-spot of civil aviation. Simulation technology can accurately duplicate the airspace operation and simulate the operation in different situations to get the relevant operation parameters. This article summarizes the process of airspace capacity assessment with the method of simulation technology and the details of simulation principle.Taking BaoTengMang approach airspace as an example, the airspace capacity assessment is studied. The simulation results show that the proposed method can accurately obtain the time, delay level and control load of the aircraft passing through the controlled airspace. Compared with the traditional method, the more reasonable airspace capacity can be obtained by considering the delay level and control load.

Qiang Wang

Research on Fault Diagnosis of INS/GNSS/CNS Integrated Navigation System Based on GA-BP Neural Network

Aiming at the shortcomings of the current polar navigation, INS/GNSS/CNS integrated navigation system is pro-posed to improve the support ability of polar flight navigation. The fault diagnosis of INS/GNSS/CNS integrated navigation system is an important means to improve its reliability. The basic concept of BP neural network is introduced. The BP neural network optimized by genetic algorithm is raised for fault diagnosis of integrated navigation in view of the shortage that BP neural network is easy to sink into local minimum. The flow chart of GA-BP neural network and the structure model of fault diagnosis for integrated navigation are designed. The simulation test is carried out according to the algorithm and fault diagnosis model. The input parameters of BP neural network are optimized based on initial simulation. The simulation finally shows that the error between the output value and the expected value of GA-BP neural network is less than 1%, the simulation proves the reliability and accuracy of fault diagnosis for INS/GNSS/CNS integrated navigation system based GA-BP neural network.

Qiang Zhang, Peng Ji, Hanyu Wu, Haobo Jiao, Rui Zhou

System Maintenance Method Based on the Mean Residual Life-Importance Measure

The aviation product production system is the basis for the rapid development, finalization, and equipment of weapons. Although the reliability optimization problem of aeronautical product production system has been paid great attention, the importance method is rarely considered by scholars to solve this problem. Based on the average remaining life of the aerospace product production system, this paper proposes a novel importance measure called the mean residual life-reliability importance measure (MRL-RIM). Then, a system reliability optimization model is established, and the MRL-RIM based genetic algorithm is developed to address the model. Numerical example simulations verify the performance of the proposed algorithm, and the analytical result shows the effectiveness, stability and convergence of the importance regarding to the average remaining life.

Zhang Zhengxin, Gao Hengyi, Cheng Luming, Li Xiaohua, Deng Qianbao

Study on Heat Transfer and Flow Resistance Characteristics of Typical Heat Exchanger Tube Based on Adaptive Heat Transfer Enhancement Method

Aiming at improving heat transfer efficiency of heat exchanger tube, this paper proposes two types of tape fitted in tubes with adaptive transform capabilities(different twisted ratio and shrink ratio at different temperature) and study on the heat transfer and flow characteristics inside the tube. In this study, the performance of inserts is simulated by commercial computational fluid dynamics (CFD) solver. Two types of inserts are presented as twisted tape and ripple tape. To value the performance of the tapes, the results simulated by CFD are presented in dimensionless form such as Nusselt number(Nu), friction factor(f) and performance evaluation criteria (PEC). Meanwhile, through the results, several dimensionless correlations are developed to predict the heat transfer characteristics and flow resistance of the heat exchanger tube with different types of tape.

Yongxiang Ren, Xiao Yu, Bensi Dong

A UAV Collision Avoidance System Based on ADS-B

Accompanying with UAVs widely used and technological development rapidly, there have been lots of unimagined trouble appearance in UAVs operations management. This article, in the context of national security, analyses the problem to surveillance and management UAVs, proposes to use ADS-B In technique to achieve situational awareness, make conflict prediction, then introduce the design of UAV Collision Avoidance System airborne device, which is designed to detective the potential conflict threat in air. Particularly, the airborne device has been evaluated on the basis of the strict weight, dimension, power, and costs. Experiments show that the UAV Collision Avoidance System Based on ADS-B IN is convenient, practical, and cost-effectiveness, it can help UAV detection of manned aircraft, the potential flight conflict in advance to predict and avoid, effectively reduce the probability of conflict.

Lin Lin, Yao Cheng, Liu Zhiyong, Liu Yinchuan, Li Nisi

The Simplest Method to Determine Cure Kinetics

Dynamic differential scanning calorimetry (DSC) experiments of a single part epoxy paste adhesive SY-H2 were performed at multiple heating rates (β) ranging from 1.25 to 160 K/min. Test results of DSC were analyzed in different ways, which the initial cure temperature (Ti), the onset temperatures (Tonset), peak temperatures (Tp) and the finishing temperature (Tf) of DSC curves were both taken into consideration to calculate the apparent activation energy (Ea). Based on changes of the onset temperatures or peak temperatures (expressed as T*) with different heating rate (β), a linear equation, $$T^{*} = T_{1} + \Delta Tln{\upbeta }$$ T ∗ = T 1 + Δ T l n β , has been obtained to determine the curing temperature parameters more reasonably. The above equation can be used to explain some laws of higher or lower of apparent activation energies (Ea), by which the apparent activation energy (Ea) nearly equals to $$RT_{1}^{2} /\Delta T$$ R T 1 2 / Δ T .

Haitao Qiao

Computational Prediction of SiCf/SiC Stiffness and Thermal Residual Stress by 3D Micro-scale FEA Methods

Ceramic matrix composites (CMCs, e.g. SiCf/SiC) are applied widely in hot-section components of aeronautics and astronautics. The macroscale mechanical properties of CMCs and the thermal residual stress (TRS) created during preparation can be easily obtained by standard tests. However, in the material design stage, it will result in waste only through testing validation. Precise virtual simulation technology (VST) is extremely useful on predicting materials’ performance and giving optimal strategies to materials designers. Under this mean, the present work is mainly focusing on predicting the macro-stiffness and TRS for SiCf/SiC composites. The microscale representative volume elements (RVE) model with period boundary condition (PBC) is used to calculate the elastic modulus in fiber direction and two fiber’s normal directions adn shear modulus of in-plane and out-plane. Besides, in the 3D microscale FEA model specialized for TRS calculation, parameters effects of homogeneous and anisotropic interphase modulus and interphase thickness are investigated.

Fei Li, Bin Liu, Nongyue Gao, Xiaoping Zhong, Min Chang, Laifei Cheng

Assessment of Crash-Resistant Helicopter Fuel Tank with Composite Compartment Simulation for Drop Test

Investigations on accidents of helicopters show that the death toll led by post-crash fires during helicopter crashes is most. Therefore, severe requirements for fuel system certification were built up. Now, fuel system crashworthiness has become the first concern in the design of helicopter fuel system. In this study work, a finite element model for a crash-resistant fuel tank with two fuel bladders and its composite fuel tank compartment was introduced. The interaction between fuel bladders and composite fuel tank compartment were investigated by fluid-solid coupling. Experimental drop test was performed utilizing real fuel tank simulacra. The data obtained were used to validate the fuel system finite element model. The failure of the fuel tank was acquired. Results of simulation were verified by the drop test. A good experimental-numerical correlation was obtained. It shows that numerical method is valuable for the design of crash-resistant helicopter fuel tank. The simulation method is reliable. The experience acquired in this study work will contribute to accomplish the certification of a modified helicopter fuel tank configuration. But its original configuration should be certified by drop tests previously.

Hongyan Zhu, Gang Wang, Yingjie Niu, Jinhua Cao, Fei Yuan, Shaobo Gong, Chunde Wang, Changliang Lin

Numerical Investigation and Analysis of Gas Leakage Process in High-Pressure Duct of Civil Aircraft

The high-pressure duct system is used in environmental control system of civil aircraft, which provides the fresh air to the cooling system. Once the gas in the duct system leaks, it can cause serious damage to the safety of the surrounding environment. During the design of high-pressure duct system, the gas leakage process needs to be studied, and the heat transfer and flow characteristics should be analyzed to evaluate the effect of the gas leakage on the surrounding environment. In this paper, the three-dimension dynamic simulation method is applied to obtain the gas leakage process in the high-pressure duct system, and the fluid-structure interaction is also considered. Based on the numerical simulation results, the variation of the heat transfer and flow characteristics of leaked gas with leak-age time is obtained; the influence factors of the gas leakage process, including the inlet pressure and the air-layer sealing, are studied. The results show that, the pressure ratio at the leakage holes has a significant effect on the heat transfer and flow characteristics for gas leakage process, and the high-pressure ratio leads to the shock wave of the gas, which decreases the detection accuracy of the leakage gas in the high-temperature and high-pressure duct system.

Yifei Yang, Chao Liu, Shenghua Yang

Research on Typical Joint Technology of Composite Stiffened Skin-Fuselage Frame

The T-joint structure is a typical stiffened skin - fuselage frame joint and an important component in the integral design of composite material. Delamination of the interface between skin and frame is a typical failure mode of T-joint. Z-pin can significantly improve the interface performance between skin and frame. In this paper, the damage process and failure mode of z-pinned joint of the T-joints are studied through simulation and experiment. First, pull-out strength experiments are performed to determine the failure modes of z-pinned joint of the T-joints. The influence of clamping span on the pull-out load is also studied in the T-joint experiments. Our results show that z-pin can significantly improve the ultimate pull-out load and connection efficiency of composite T-joint. The improvement effect became more obvious with the decrease of clamping span. Second, the bilinear cohesive behavior and nonlinear spring elements are introduced to simulate T-joints the delamination of interface and the effects of z-pin under the pull-out load. Simulation results are in good agreement with the experiments, which verifies the reliability of the interface damage simulation of cohesive behavior contact and the z-pin simulation of nonlinear spring element. Our simulations and experiments reveal similar damage failure modes together.

Liu Han, Hui Qi, Rui Li, Pingan Liu, Shifeng Li, Zhen Zhan, Jinliang Wang

Fatigue Crack Growth Performance of Refilled Friction Stir Spot Welds in Similar and Dissimilar Aluminum Alloy Joints

Refilled friction stir spot weld (FSSW) is recognized as a potential replacement for riveting due to many advantages. For the application in aircraft structures, fatigue crack growth (FCG) behavior is essential to maintain structural integrity, and has been seldom reported up to now. In this work, FCG behaviors of similar and dissimilar refilled FSSW joints for typical aluminum alloy sheets were experimentally studied, and were compared with those of riveted joints. The mechanisms for the relevant phenomena were also investigated with the aid of fractography. The initial crack along the central line of the spot welds was found to tend to propagate straight through the weld in similar 2A12-T42 joints, while it was more likely to propagate along the periphery of the refilled stir zone in similar 2024-T3 joints. Due to finer grain in the stir zone and the “bridging effect” of the welds, FCG rate of both 2024-T3 and 7075-T62 refilled FSSW specimen was lower than that of base material or corresponding riveted specimen (before the crack propagated into the rivet hole). However, riveted specimen possessed longer fatigue life because the crack was stopped for a long test period when it grew into the rivet hole.

Haiying Zhang, Binwen Wang, Gang Li, Wenkui Chang, Dengke Dong

Clocking of Stators and Rotors in a Three-Stage Axial Turbine

The paper presents a numerical investigation on the clocking effect in a three-stage axial low pressure turbine. Equal pitch configuration was applied to reduce computation cost. The flow field was solved by commercial unsteady CFD solver. The performance for different clocking configurations is compared; the result indicates that the key of the clocking effect on overall efficiency is the loss variation of the downstream row in the clocking pair. For such row the loss-minimum clocking configuration at specified spanwise section is where the wake fragment enters the passage near the leading edge, especially from the suction side. The loss-minimum clocking configuration of entire span is identical to that of the spanwise section where the wake fragment strength reaches maximum. The entropy generation rate in the passage of the downstream clocking row is compared and analyzed. The result shows that the wake fragment decreases the time-averaged loss generated near its avenue. When the wake fragment enters the passage from the suction side of the leading edge, its avenue is more close to the high loss region, resulting in lower overall loss of the passage. A neighboring wake fragment avenue at suction side brings the risk of larger separation, but the impact on performance is not dominant in the studied model. The interaction of stator clocking and rotor clocking in the same stage is also studied. The effect of rotor clocking is shown to be slightly affected by the clocking of upstream stator, but the row-by-row clocking still yields a full clocking configuration with high efficiency.

Zongqi Lei, Lei Zhao, Weitao Hou, Shiji Wang, Jing Wang

Flow Prediction of Aero Engine Driven Pump Based on QPSO-LightGBM

The flow rate of aircraft hydraulic system is one of the important parameters to measure the performance of air-craft. The stability of flow rate of hydraulic pipeline is related to the safety of hydraulic system and even aircraft flight. Aiming at the problem that it is difficult to measure the load flow of aircraft hydraulic system, a prediction method based on ensemble learning for the load flow of Engine Driven Pump (EDP) is proposed. According to the different working conditions of EDP, the QPSO-LightGBM intelligent integrated learning algorithm model is established. Through Quantum Particle Swarm Optimization (QPSO) algorithm optimizes the super parameters of Light Gradient Boosting Machine (LightGBM) algorithm, and realizes the regression prediction model of load flow by three factors: system oil pressure, temperature and high pressure oil filtration pressure difference. Finally, by com-paring multiple linear regression, random forest and XGBoost, the Root Mean Square Error(RMSE) of the proposed method is 1.0152 and the goodness of fit R2 has reached to 0.9988. The effectiveness of QPSO-LightGBM method is verified. The method can provide technical support for the fault diagnosis of aeronautical hydraulic system.

Yangyang Zhao, Wei Niu, Meinan Wang

High-Entropy Ceramics Diborides for Hypersonic Applications

High-entropy ceramics diborides (HEBs) is a new series of high-entropy materials (HEMs), with excellent ultra-high temperature stability and ablation resistance. HEBs possess ultra-high melting point, lower thermal conductivity and promoted mechanical properties compared with current ceramics, which can meet the requirement of hypersonic vehicles, especially the local hot spots such as sharp leading edge and combustion chamber. Based on the crystal structure, the designation, the preparation methods and properties of HEBs, the research progress of HEBs is detailed introduced. The quasi-2D hexagonal crystal structure entrusts the excellent properties of HEBs. Through several preparation methods such as spark plasma sintering (SPS) and hot pressing, not only dense bulk materials but porous light coatings can also be processed. Based on the characterization results, HEBs usually own ultra-high hardness and strength, while their toughness is in urge need to promote. Moreover, the porous HEBs structure can efficiently decrease the thermal conductivity, which may play a significant role in the hypersonic applications.

Sisi Xiang, Chenhui Du, Xuewei Cao, Lang Chen

Surface Deposition Characteristics on Long Thermal Duration Within Treated and Untreated Stain Steel Tubes of Supercritical Kerosene RP-3 Fuel

Aimed to the development of aero-engine cooled cooling air (CCA) technology, the thermal deposition characteristics of kerosene fuel RP-3 have been experimentally studied for long thermal duration at supercritical pressure. The fuel has been heated for 5 h in the three different stainless steel and passivated tube respectively at the pressure of 5 MPa. During the test, the fuel inlet and outlet temperature were fixed at 400 and 723 K with 3 g/s flow mass rate. In this work, it was found that the electrolytic passivation treatments could reduce the total deposition amount about 71.8%, while the pre-oxidized treatment gives nearly the same deposition amount compared with the as-received SS321 tube. In contrast to our previous short thermal duration experiments (1 h), the 5 h thermal duration deposition mechanisms have been discussed on the treated tubes surface based on the integrated analysis of local inner wall temperature, surface deposition distribution, SEM morphology and chemical composition.

Kun Zhu, Xiao Yu, Guoqiang Xu, Jiankun Li, Chunlei Zhang, Maoguo Cao

Simulation and Verification Method of Aircraft High Intensity Dispatch Capability

High intensity flight test is of great significance for flight test. Due to the complexity of high intensity flight test, it is an important research direction to use simulation to guide flight test and use flight test data to modify simulation test model. In this paper, the sunrise sortie rate, an important index of high-intensity flight ability, is taken as an example to carry out the simulation verification combined with the flight test situation, and the international famous simulation software simlox is used for the simulation comparative analysis. The model has high accuracy and strong usability. This method can provide reference for the implementation of the follow-up high-intensity flight test and provide the basis for the design change.

Tao Ma, Chengyu Ju, Huaigeng Qu

Research on Ground Verification Technology of Civil Aircraft EWIS Airworthiness Compliance

At present, civil aircraft EWIS is highly concerned by all parties, especially for safety assessment. The requirements of safety analysis, data acquisition and evaluation methods related to safety in actual flight state of EWIS system, on-board inspection strategy and related maintenance evaluation need to be further explored and studied. This paper studies the inspection methods of EWIS airworthiness compliance, describes the failure mechanism of friction, aging and damage of EWIS from qualitative and quantitative aspects, designs special inspection methods for different regions, and calculates weight by triangle fuzzy method, and evaluates the optimal type of EWIS comprehensively, and obtains the optimal application case.

Chengyu Ju

Aviation Support Equipment Test Based on System Engineering

In this paper, the system engineering method is used to analyze the current situation and existing problems of aviation support equipment test, and the key problems that need to be paid attention to in the development of aviation support equipment test are put forward, hoping to further promote the aviation support equipment test work.

Lianhe Zhang, Chengyu Ju

A Distributed Control Scheme for Multi-parallel Connected Generators of Power Supply System in More Electric Aircraft

The demand of More Electric Aircraft (MEA) increases with the need of on-board electrification system for future aircraft. In a traditional power supply system of MEA, electrical power is only extracted from a high pressure spool, which has a negative impact on engine performance. In this paper, a multi-parallel connected generator system is proposed to increase redundancy and robust of a power supply system in MEA. Considering differences in structure and electrical parameters among generators, a Band-Pass Filter (BPF)-based control scheme is proposed to achieve power sharing among generators without communication lines. Finally, extensive simulation results are further provided to confirm the validity and effectiveness of the distributed BPF-based control scheme for multi-parallel connected generator system in more electric aircraft.

Hong Li, ZhengDa Zhao, Xiang Lei, ShuangXin Zhao, Long Xu

Design of Recovery Control Law for Aircraft in Low Energy State Based on Total Energy Control

In order to solve the difficult problem of low energy state recovery caused by the speed neutral static stability of modern fly-by-wire civil aircraft, a design method of low energy recovery control law was studied. First of all, based on the principle of total energy control, the speed-height decoupling control method was studied according to the characteristics of the civil aircraft instrument landing system (ILS). Secondly, the recovery control laws for the low kinetic energy state and the low potential energy state were designed respectively, and the relationship between them and the original control law of the aircraft was clarified. Finally, a certain type of dual-engine branch line telex airliner was taken as an example to verify the effectiveness of the low energy recovery control law. It is shown that the control law was helpful to reduce the workload of the pilot and improve the recovery efficiency. The research results can provide a theoretical reference for the control law design of low energy recovery.

Junping Chen

Key Parameters Selection of Single Engine Failure Takeoff Test for Real-Time Monitoring Based on Flight Simulation

Single-engine failure takeoff test is one of the high-risk subjects, and it must be tested to demonstrate the airworthiness compliance of civil aircraft. Many accidents have occurred in previous aircraft types in flight tests. In order to improve the risk estimation ability of ground monitoring, firstly, general process of the test was studied according to the relevant requirements of CCAR25 for single-engine failure takeoff test. Secondly, possible risks in the test process were analyzed based on the aircraft dynamics characteristics, and test evaluation parameters and risk control parameters were proposed. Thirdly, the real-time acquisition and display comparison methods of all selected parameters were clarified. Finally, the effectiveness of the selected key parameters, used in real-time monitoring and risk assessment of single-engine failure takeoff test, was verified by taking a certain type of dual power transmission transport aircraft as an example. The research results have certain reference value for the risk control of civil aircraft single-engine failure takeoff test.

Junping Chen, Yi Wang

Bolt Pre-tightening Force Monitoring Based on Stacked Autoencoder

The loosening of the bolts in the bolted connection structure will cause damage to the structure and even lead to disasters. In order to solve these problems, this paper combines the correlation analysis of structural vibration response under environmental excitation and deep learning technology based on stacked autoencoder (SAE), and proposes a bolt pre-tightening torque monitoring method based on structural vibration response. Firstly, using the time domain vibration response data of the structure under environmental excitation as the original information, the correlation index based on the inner product matrix method can be obtained to describe the structural health characteristics. Then, a stacked autoencoder for deep learning is constructed by the correlation index. Furthermore, the feasibility and effectiveness of the method are verified by experimental research on the bolt pre-tightening torque monitoring in the bolted connection plate. The results show that the method proposed in this paper has high accuracy in the monitoring of bolt pre-tightening torque.

Zhang Minzhao, Wang Le

A Method for Analysis of Environmental Sensitive Stress in the Actuator Enhanced Test

In order to determine the influence of environmental sensitive stress in the actuator reliability enhancement test, improve product reliability, a certain type of actuator is taken as the research object in this work. From the perspective of environmental factors of fault modes, an environmental sensitive stress analysis method based on Analytic Hierarchy Process (AHP) is adopted to analyze nine environmental sensitive stress factors (including high temperature stress, low temperature stress, rapid temperature change stress, vibration stress, impact stress, acceleration stress, temperature height stress, damp heat stress and working load stress) of three inpatient fault modes, namely piston oil leakage, servo valve failure and plate valve failure. The influence weight of each environmental influence factor is obtained, and the results are consistent with the known empirical data of this type of actuator, which proves the effectiveness of the analysis method based on Analytic Hierarchy Process (AHP) for the environmental sensitive stress analysis of the actuator reliability enhancement test.

Jiwen Gao, Shaoguang Du, Tongming Sun, Cheng Zhou, Yujiang Zhai

Research on Performance Degradation Characteristics of an Airborne Hydraulic Actuator

Degradation characteristics analysis is an effective and reliable method for life analysis of airborne hydraulic actuator. Compared with life data analysis, degradation score can usually provide more accurate evaluation results. In this paper, a certain type of airborne hydraulic actuator is taken as the research object. Based on the results of graphic analysis and distribution characteristics analysis, the degradation characteristics of performance parameters and rocker shaft clearance structure parameters are analyzed. The results show that the extrapolation method can be used to predict the product failure time based on the product performance degradation data, it can be used to quantitatively evaluate the performance degradation characteristics of actuators and provide useful support for the quantitative evaluation of actuator life.

Jiwen Gao, Shaoguang Du, Yongbin Li, Tongming Sun, Ting Wang

Design of a Quadrotor Attitude Controller and Throttle Acceleration Autopilot Based on Forward Modeling

Quadrotors are currently of widespread use in many commercial and military applications, thus, any development aiming at increasing their flight performance is of considerable relevance. Both the model structure and main dynamical parameters of a quadrotor during forward flight are different from those present when hovering. This results in a poor performance of any controller designed for hovering equilibrium, when applied to forward flight scenarios. Aiming at this problem, we propose a design methodology for a quadrotor attitude controller and throttle acceleration autopilot, based on forward modeling. Firstly, the forward dynamics is modeled via system identification and designed experiment. Then, utilizing the linearization results, a frequency domain analysis method is investigated for tuning the parameters of attitude cascade PID controller of quadrotor. The three-layer structure requires it to be designed separately, where the inner loop solves the stability problem and the outer one improves the response performance. And this work regards crossover frequency and phase margin as indicators. Next, a novel closed-loop throttle autopilot with acceleration feedback is constructed to control the vertical movement fast and accurately. The control command in throttle channel is given from the relationship between equilibrium throttle and vertical acceleration, which will be processed by a PI correction and a first-order low-pass filter. Finally, the numerical simulations and comparisons are carried out to demonstrate the strong stability and transient behavior of the proposed scheme in different working regimes.

Kaiyang Guo, Defu Lin, Bin Li, Tao Song, Luyao Zang, Yifang Yuan

Research on Flight Test Technology of Turboshaft Engine Installation Performance Loss

After the turboshaft engine is installed on the helicopter, it is usually necessary to carry out the flight test of installation loss. The inlet temperature and the inlet pressure of turboshaft engine shall be measured. According to the measurement results and comparison of the performance data of turboshaft engine on the helicopter and the test data received from ground bench, the engine performance changes on the helicopter can be analyzed. In this paper, based on the analysis of the reasons for the loss of engine installation performance, the appropriate test method is selected and the flight test programs are defined, in order to realize the accurate measurement of the engine installation performance loss test, which provides a reference for the test of the engine installation performance loss.

Ming Yan, Chunyu Yang, Xin Chen

On the Correction of k-ω SST Turbulence Model to Three-Dimensional Shock Separated Flow

Conventional eddy-viscosity turbulence models always overpredict the separation in three-dimensional shock separated flow due to inadequate Reynolds stress prediction. Grid and scheme convergence studies also give unreasonable tendency since the flow mechanism is not properly revealed from turbulence modeling perspective. Two corrections for this defect are proposed based on k-ω SST model. One directly aims at modifying the Bradshaw assumption, which was derived from observation of two-dimensional attached flow but will prevent the increasing of eddy viscosity in three-dimensional shock separated cases. The other one constructs a correction term to the dissipation term of specific dissipation rate equation by the production and dissipation of turbulent kinetic energy, which exists apparent imbalance in non-equilibrium flow. A switching function is also designed to control this correction term by a special ratio of “modeling” length scale and “required” length scale for the log layer. Two corrections are validated by the ONERA M6 wing at α = 6.06°, and the results shows better agreement with the experiment than that of the Reynolds-stress model. Grid convergence study, Reynolds stress analysis and verifications on other angles of attack are also conducted to show the validity and applicability of the proposed correction approaches.

Yiming Du, Bowen Shu, Zhenghong Gao, Shengyang Nie, Rui Ma

Research and Implementation of Centrifugal Harmonic Force Generator System for Vibration Control

The active vibration control system is the main path to restrain the low frequency vibration caused by the helicopter rotor system. This paper puts forward the active vibration control system of centrifugal harmonic force generator driven by permanent magnet brushless DC motor, expounds its composition and working principle, and thoroughly analyzes the output force regulation mode of the actuator. Subsequently, the 180 W/2588 N low-power high-torque centrifugal harmonic force generator and its control system are developed successfully, and its key components such as motor parameters, isolation drive circuit and bus support capacitance are designed. Finally, the integrated experimental platform for active vibration control is constructed and verified by experiments. The experimental results suggest that the output force regulation effect of the actuator is excellent, which directly lays a theoretical and technical foundation for the application of centrifugal harmonic force generator in the new generation helicopter.

Mingliang Hu, Lingwei Wang, Kui Chen, Wen Yan

Research on Simulation of Composite Material Assembly Process Based on Key Production Resources

The proportion of high-performance composite materials used in the aerospace industry has increased significantly. In the field of aircraft assembly, although there has been in-depth research on the assembly process simulation of traditional metal winglet parts, there are relatively few research cases on the assembly process simulation of composite winglet parts. In this paper, the production line is first investigated in the trial production stage of a typical composite small wing surface component. Draw a process flow chart, including the preceding process, process time and key resources. Then calculate the logistics path of the entire production line, and get the basic principles of the typical digital factory layout. Then build a 3D model of the digital factory based on CATIA. Finally, a process simulation model is established based on MATLAB to calculate the typical part capacity, resource utilization, resource waiting rate and the waiting rate of each process under different production resource constraints. This model provides decision-making reference for plant equipment layout and capacity analysis of product batch production investment.

Yanru Liu, Kai He, Peng Tang

The Research Progress and Prospect of Key Technologies in the Interior Weapon Cabin

The loading mode of weapons has always been a key issue in the field of development of fighter aircraft. With the development of high mobility, supersonic cruise, over the horizon combat and good stealth, more and more fighters choose interior weapon cabin. However, the interior weapon cabin system is complex and involves many research fields, so the research is challenging. In recent years, the development of advanced weapon technology, thermal protection technology and artificial intelligence has brought a new direction to the research of interior weapon cabin. Based on the introduction of typical aircraft weapon loading modes, this paper summarizes the key technologies of interior weapon cabin, and prospects the future development direction.

Jinglong Wan, Zhili Tang

UAV Aerial Photography Target Detection and Tracking Based on Deep Learning

With the development of aviation technology, UAV technology has gradually become a research hotspot in the aviation field, and it plays a vital role in civil and military construction. Target detection and tracking of aerial video is a key technology for UAV reconnaissance, disaster relief, enemy monitoring, and military strikes. This paper studies the YOLOv3 target detection algorithm and SiamMask target tracking algorithm based on deep learning, and compares these algorithms Based on the situation of long aerial photography distance and small target, the algorithm is improved and fused to realize rapid target identification and tracking under UAV aerial photography. At the same time, in order to simplify the model and accelerate the speed of model training and reasoning, the simplification of the tracking algorithm model is studied. Finally, an aerial photography experiment was conducted in an outdoor environment to verify the effectiveness of the UAV target detection and tracking algorithm.

Xiaohua Li, Feiyang Wang, Aiming Xu, Guofeng Zhang

Arc Fault Recognition Method Based on Current Characteristics of Electrical Equipment

In order to detect arc fault in line, an arc fault identification algorithm is proposed. The current waveform of common household and office appliances in normal operation and the current waveform of arc fault and point contact arc fault in its branch are tested. The information dimension of current phase plane diagram is calculated based on fractal theory, and the arc fault identification model. Phase space reconstruction of current waveform, The Information Dimensions of Current Phase Plane Based on Fractal Theory is considered as one of the characteristics of arc fault identification, then the current zero-off time is taken as the second characteristic, the arc fault identification model based on SVM is established. The simulation result shows that: the proposed algorithm can effectively identify arc fault and provide a reference for the development of a new type of AFCI with fault location function.

Bao Jieqiu, Wang Shuli, Wang Sen, Li Pengbo

A Landing Trajectory Tracking Controller for Fixed-Wing UAV Based on Iterative Learning Control

Landing is the most critical flight phase of a fixed-wing Unmanned Aerial Vehicle (UAV). An accurate trajectory tracking during the landing phase determines whether a UAV can be safely recovered, while the non-linear trajectory in the flare phase makes it difficult to be tracked accurately. Consider that the trajectory in the flare phase is usually pre-defined in many cases, in this paper, we propose a more practical way that use Iterative Learning Control (ILC) to gradually determine the proper input to the UAV by repeating the landing maneuver. The tracking error of each attempt is stored, processed, and becomes the compensation for the next flight. To minimize the risk, these attempts can be performed in mid-air until the tracking error meets the requirements. In this paper, an analysis based on the nonlinear aircraft dynamic model shows that the tracking error caused by model inaccuracy cannot be compensated by the integrator. Then, An ILC based landing trajectory tracking controller is designed. Simulation results demonstrate the effectiveness of the proposed ILC controller.

Jun Li, Ziqi Jia, Tianyi Liu

Identifying Flight Trajectory Patterns via a Density-Aided Hierarchical Clustering Algorithm

Identifying flight trajectory patterns is a vital task that helps controllers better understand the flight operation mechanism, so as to effectively recognize flight anomalies and manage traffic flow, etc. However, flight operation is sensitively affected by the weather and instant airspace regulation, making the flight trajectory pattern too intertwined to be easily distinguished. In this work, we propose a trajectory pattern identification method based on a density-aided hierarchical clustering algorithm. This method employs a weighted trajectory clustering mechanism to keep the minor trajectory patterns from being improperly “swallowed” by other large trajectory patterns. Experimental results show that the proposed method can explicitly distinguish different trajectory patterns and achieve more accurate results than existing approaches.

Zhuxi Zhang, Yichong Chen, Jing Fang, Xueyang Zhou, Yuhang An, Xi Zhu

Controller Design for Electro-mechanical Actuators

Because of the advantages of being reliable, saving weight, size and cost, reducing maintenance fees and environmental impact, More Electric Aircraft (MEA) has attracted more and more attention, and Electro-mechanical Actuators (EMA) are the realization of the MEA concept. This paper introduce the cascade controller design for the EMA of the flight surface, which includes current loop, speed loop and position loop. The simulation results using anti-windup method all meet the overshooting requirements of 5% and show the effectiveness of the design.

Lingling Jiang, Zhonghu Sun, Xianjian Jia, Xiaoyan Li, Wulong Duan

Flowfield Characteristics Under the Interactions Between Pressure Waves and Inflated Cylindrical Membrane

The flowfield characteristics under the interactions between pressure waves in the external flow field and inflated cylindrical membrane are studied. The results show that during the interaction between incident shock and mem-brane, complex shock reflections are induced. There are Mach reflections appeared at the up and down sides of the membrane. Then the triple points and Mach stems are formed. By the influence of the Mach stems and high-pressure gas, recompressed shock structures are formed behind the Mach stems. The diffracted Mach stems are intersected by each other behind the leeside of the membrane, and formed complex strong discontinuity structures.

Conglei Wang

Encoder Positioning Manual Ultrasonic C-Scan Testing Method and Applications

To solve the problems that traditional manual inspection results cannot be visualized and automatic detection equipment is complex and non-maneuverable, a manual ultrasonic C-Scan testing method based on encoder positioning is proposed. By analyzing the characteristics of the ultrasonic A-Scan signal, an acquisition method for ultrasonic A-Scan signal characteristic parameters is established. Based on the encoder position technology, an encoder positioning manual ultrasonic scanning (EPMUC) testing system is proposed. The EPMUC testing system, which is composed of an acoustic system, positioning system and data processing system, is established. Manual ultrasonic C-Scan tests are performed on parts of a titanium alloy-brazed honeycomb sample with manual preset debonding defects and an actual titanium alloy-brazed honeycomb part with the EPMUC testing system. The test results show that the EPMUS system can effectively identify the honeycomb area and honeycomb wall area in the honeycomb structure and can detect manual preset debonding defects in the sample. The maximum detection deviation is 4.4 mm, and the imaging accuracy can reach 1 mm.

Tianhang Fu, Songping Liu

Cost Index Optimization Considering the Impact of Carbon Emissions

With the International Civil Aviation Organization’s global goal of “Carbon Neutral Growth” and the implementation of the Carbon Offsetting and Reduction Scheme for International Aviation, airlines face carbon emissions related costs, as an increase in operating cost. At the same time, the cost index is a common measure for reducing operating costs in flights operations, while the current cost index calculation method does not consider the cost of carbon emissions. By optimizing the cost index calculation method, this paper identifies the weighted cost index that takes into account the impact of carbon emission costs. Further based on Boeing's performance calculation software (PET), the impact of two different cost indices on the total operating costs are calculated and analyzed, comparing the economic operating efficiency. The results show that when using the weighted cost index, on the 1000nm route, the carbon emissions can be further reduced, with effects on saving total operating costs. The weighted cost index can be used as an effective measure to improve operating economics for airlines.

Siying Li, Yuxiao Luo, Yi Yang

Single-Engine Landing Adaptive Reconfiguration Controller of Carrier-Based Aircraft

This paper designs the adaptive reconfiguration controller of the carrier-based aircraft landing with the single-engine failure. It mainly adopts the combination of reconstruction control and LQR, and designs an adaptive reconfiguration control law to realize a single-engine carrier aircraft gliding at a constant speed and the track correction. When the single engine fails, the landing control law of the carrier-based aircraft is switched to the control law designed in this paper. Through simulation and comparison of the classic control methods, the stable control of the single-engine landing adaptive reconstruction is realized.

Yang Zhang, Yi Zhou, Xianrong Yan, Dawei Yin

Performance Analysis and Research on the Containment Structure of Ultra High Speed Turbine in ATS

Aiming at the containment structure of an aero-engine ultra-high speed air turbine starter, the containment capacity was analyzed and verified. The Johoson-Cook constitutive model was used to simulate its containment capacity with LS-DYNA software, and the containment test was carried out on the ultra-high speed rotating test bench. The experimental results show that: after the turbine disk is broken and files out, the main characteristics are the impact on the guide shell and the inner wall of the containment ring, and the circumferential sliding and scraping movement along the inner wall of the containment ring. The containment ring absorbs energy through its own deformation and the scraping and sliding between the inner wall and the turbine. The experiment results are in good agreement with the model simulation results, which shows that the containment structure can restrain the broken turbine disk, and has good containment capacity. The research results have a good guiding significance for the containment structure design of air turbine starter.

Cong Jiang, Xin Xiong, Mian Liu, Qi Zhang

Vulnerability Modeling and Protective Measure Assessment Method for Ground Support Aircraft

In order to decrease the vulnerability of ground support aircraft under fragment/projectile attack, a vulnerability model of a ground support aircraft was established, and the vulnerability of the ground support aircraft in the typical attack direction was calculated. According to the geometric shape of the ground support aircraft and the distribution of critical components, the ground support aircraft is divided into different areas, and the armor protection efficiency of each area is assessed. The results show that the cockpit area, the front fuselage fuel tank area, and the rear fuselage fuel tank area have high protection efficiency, and these areas can be protected first when the armor weight is limited. On this basis, flexible use of vulnerability reduction measures, targeted reduction of highly vulnerable components, and repeated iterative analysis to achieve vulnerability index requirements are performed. Finally, a numerical simulation test was carried out on the A-10 ground support aircraft. After the vulnerability was reduced, the index design requirements were met under the B and C level kills, which verified the feasibility of the proposed method.

Wan Li, Yang Pei, Yuxue Ge, Mingsuo Li

Design Simulation of the Low Fatigue Life of a Fan Blisk Using the Simulating Specimen Approach

The development of blisk structure has made the low cycle fatigue (LCF) life test more expensive for the critical components. This paper aims at design several simulating specimen to simulate the working condition and stress distribution of a high-loaded fan blisk. The finite element analysis was performed to confirm the constraining locations of the fan blisk. Afterwards, the LCF life of the blisk was calculated according to Mason-coffin equation and the total damage methods with the predicted maximum allowable LCF life reaching 158352 cycles. Meanwhile, the crack propagation simulation was carried out to figure out the propagation cycle life of the critical locations. The predicted cycle life of the fan blisk is about 4276 and 3991 cycles using the semi-elliptical crack and the 1/4 surface corner cracks. Then, by optimizing the three critical parameters with regard to the stress gradient of the specimen, the optimum simulating specimen were confirmed and tested in the thermo-mechanical fatigue test rig. Results comparisons show that the LCF life of the designed simulating specimen is approximate 153339 cycles, which is content with the calculation. The simulating specimen approach proves to be a reliable and accurate way to validate the cycle life of the engine critical components.

Qing Du, Yixiong Liu, Jian Zhang, Yong Guo, Yunwu Wu

Three-Dimensional Aerodynamic Characteristics of Fan Rotor with Large Bypass Ratio in Distorted Flow Field

A three-dimensional numerical calculation code based on body force model has been developed and used to predict the intake fan of high bypass ratio turbofan engine performance with inlet distortion. The program can predict the characteristic curve of the fan rotor with high accuracy, and can describe the flow field of the fan reliably. The program is used to study the fan rotor characteristics of turbofan engine with large bypass ratio in circumferential distortion flow field, and the three-dimensional characteristics of the distorted flow field are obtained. The results show that the nununiformity of total pressure be weakened, total pressure distortion always decays through the fan. The total pressure distortion in the inlet will induce the total temperature distortion in the rotor blade trailing edge. Distortion transfer coefficients in the different height of rotor blade are different, and they distribute along the radial direction.

Cong Jiang, Qi Zhang, Mian Liu, Xin Xiong

Design and Implementation of Magnetic Resonant WPT Charging Area

This paper upgrades the single-excited magnetic resonant WPT system to the multi-excited magnetic resonant WPT power supply area, and proposes a winding connection principle for constructing an omnidirectional power supply area. By changing the winding connection mode of the excitation coil, the magnetic field distribution in the wireless power supply area is changed to form in the enhanced area and weakened area of the magnetic field, the power receiving terminal can improve the degree of energy coupling and power transmission efficiency by changing its degree of freedom in the area. The distribution of the magnetic field under different winding connection modes is analyzed and summarized. In the end, the experimental results of the open resonant wireless charging area platform built by the experiment are consistent with the theoretical analysis and simulation results.

Wenxian Chen, Zhenyu Qian, Yuan Gan

Study on Aeroacoustic Noise Effect on Cockpit of Retractable Aerial Refueling Assembly

The aeroacoustic noise influence of retractable assembly on aircraft surface is researched. Aeroacoustic noise of different points on airframe is calculated for comparison between the airplane contains retractable assembly and a smooth surface airplane. The change of noise and the distribution of noise source caused by retractable assembly on aircraft surface can be obtained. A pilot ear-level plane is built for sound pressure level calculation on cockpit noise. The effect of the device protruded and retracted on the cockpit noise is analyzed. The results show that the main noise sources are distributed near protrusive pipe area and on the wall of intake cavity. The noise in middle of cabin is stronger than that in front and behind of cabin. When the retractable assembly is protruded, the noise increase from 6dB to 13dB. The noise spectrum is continuous and has characteristic of broad band, and the noise increase with the Mach number. The noise is in low frequency when retractable assembly is protruded and the noise is in medium-high frequency when the device is retracted. The results can provide technical foundation for the future aircraft noise reduction design.

Xu Gao, Zhixiong Pan, Dongqiang Zhao, Jianzhong Chai

Research on Key Technologies of Aircraft Automatic Braking System

The automatic braking system is a general configuration of advanced military and civilian transport aircraft. This paper studies the key technologies of the automatic braking system, including “multi input, multi-mode” automatic braking control logic conversion technology, automatic braking constant deceleration rate control and antiskid control compatibility technology, automatic braking course stability control technology. Based on this, a collaborative virtual simulation verification platform for aircraft automatic braking system is established, which greatly improves the efficiency of simulation test and shortens the development period of the system.

Zehua Liu, Zhenhua Zhang, Cheng Qin, Wei Li

Aeroelastic Characteristics of Fin-Actuator System Based on High Order Harmonic Balance Method and Pseudo-arclength Continuation

Although the time-domain aeroelastic analysis of the fin-actuator system is accurate, it is very time-consuming. Some work in the past used the describing function method to calculate the dynamic stiffness of the actuator, and then obtained the aeroelastic stability of the system in the frequency domain. This greatly shortened the time, but there was a loss in accuracy. In order to improve the accuracy and speed up the calculation to a certain extent, this paper uses high order harmonics to describe the response of the system. The frictional hysteresis loop is difficult to obtain a closed-form solution in the frequency domain. In this paper, a truncated Taylor series expansion is used to smooth the LuGre friction model so that the harmonic balance method can be used. The pseudo-arclength continuation method is used to solve the problem, and the bifurcation diagram of the limit cycle of the system is obtained. The results show that the method used in this paper has achieved a balance between time and accuracy in calculating the aeroelastic stability of the fin-actuator system.

Jin Lu, Zhigang Wu, Chao Yang

Analysis of Effect of Wing Layout on Aircraft Floating Characteristics

Once the engine failure or fuel exhaustion above water, the aircraft should be ditching on the water surface immediately. From the perspective of floating characteristics, the overall layout of the wings will affect the float ability obviously. The paper based on the anti-sinking theory of floating characteristics and the discrete analysis method of water intake fragments, calculating the floatation characteristics for upper monoplane and lower mono-plane in different center of gravity. The analysis and conclusion can provide a reference for the safety assessment after ditching and the emergency escape device design.

Wang Mingzhen, Jiang Ting, Zuo Zibin, Sun Feng

Application of RBF-TFI Moving Mesh Technology Based on Structural Grid in Static Aeroelasticity

In order to improve the accuracy and efficiency of static aeroelastic calculations, a structural Moving mesh technology based on Radial Basis Function (RBF) and Transfinite Interpolation (TFI) methods has been developed to perform aerodynamic/structure coupled computing. Because the common research model (CRM) will produce elastic deformation under high Reynolds number wind tunnel test conditions, the CRM-WBT0 (wing body horizontal tail 0°) configuration is selected for calculation to verify the feasibility of the engineering application of the RBF-TFI moving mesh method. Comparing the calculation results with the spring network moving mesh method based on the background grid and the lift, moment coefficient, model deformation, and pressure distribution results measured by the European Transonic Wind Tunnel (ETW), the results show that the derivatives of lift coefficient and pitch moment coefficient to the angle of attack differs from the test results by less than 0.001; the pressure coefficient distribution on the surface of the wing at the typical spanwise position near the design lift coefficient is also in good agreement with the test results; the deflection and torsion angle of the wing are almost consistent with the deformation measurement of the test model, the torsion angle error is less than 0.1°, indicating the calculation accuracy and engineering adaptability of the moving mesh technology.

Yingli Su, Fei Xue, Yong Lu, Kun Mao

A Rapid and Integrated Modeling Method of Aircraft Vulnerability Based on CATIA Analysis Simulation Module

Aircraft vulnerability modeling is the basis and prerequisite for vulnerability analysis. At present, vulnerability modeling methods include combinatorial geometry, triangular patch, and tetragonal patch. However, these methods have disadvantages such as low modeling accuracy, complex modeling process, and finite element software. Under the problems of the above methods, a vulnerability modeling method is proposed based on the CATIA Analysis Simulation module, in which the secondary development of the aircraft shape and the tetragonal mesh, materials, and attribute of the components data file are completed. In this method, the geometrical modeling and meshing are synchronized and integrated into the CATIA platform which shortens the vulnerability pre-modeling process. Taking the US “Scan Eagle” UAV as an example, the input model file for vulnerability analysis is generated. The effect of this method and the traditional finite element modeling method is compared in C and K kill levels, which verifies the validity and usability of the proposed method.

Yang Pei, Likuan Shi, Yuxue Ge, Mingsuo Li, Chunyu Bai, Yu Zhang

A Numerical Solution of a Hose-And-Drogue Aerial Refueling System: Multi-body Dynamic Model with Varying Constraints

Probe-and-drogue aerial refueling is a widely used military technique for transferring fuel between aircrafts. A dynamic model for the study of the hose-and-drogue system requires three essential elements, which are the dynamics of the bodies, the external loads and the constraints on the bodies. However, in the most advanced models, either the reel behavior is absent or the interactions between the reel and the hose are ignored. In this paper a model is presented that fully reflects the dynamic behaviors of the hose-drogue system in a multi-body dynamic approach. In the model, the hose is represented by a series of discrete links, while the reel and drogue are represented by mass points connected to the hose. The interaction between the reel and the discrete links of the hose are treated as variable constraints to accurately reflect the hose-drogue system before and during the hose-probe contact. A numerical method based on Newton-Raphson iteration is proposed to solve the multi-body dynamic system with variable constraints. A demonstrative simulation reveals the performance of the method. In the simulation result, the take-up behavior of the hose is observed, which validates the model.

Boqian Fan, Kang Ji, Jian Wang

Numerical Simulation of Heat Flow Field on the Outer Surface of the Airframe

Advances in reusable and hypersonic technology have accelerated the historic integration of transatmospheric ve-hicles, blurring the line between spacecraft and aeronautical vehicles. At the same time, MEA/AEA concept is widely used in the design of advanced aircraft developing towards electrification and intelligence, causing a lot of heat generated by Airborne electronic equipment, of which the cooling demand increases with the replacement of electronic equipment which causes the on-board electronic equipment will generate a lot of heat, and its complexity and energy requirements will increase with the replacement of electronic equipment. Therefore, the heat dissipation of the aircraft is not optimistic. As a power energy source, fuel stored in the fuel tanks around the fuselage and wings is also one of the important heat sinks of the aircraft. The heat transfer analysis of the fuel tanks is particularly necessary for the integrated thermal management of the aircraft. By computational fluid dynamics and numerical heat transfer method, the simulation calculation and analysis of external flow field and aerodynamic heating of different task profile provide the detailed outer boundary conditions for the next long endurance fuel temperature simulation and lays a foundation for the analysis and calculation of integrated fuel thermal management.

Xiaolong Tong, Zhenghong Li, Liangliang Liu, Haoyang Sun, Haichuan Jin

Robustness Analysis of Two Advanced Flight Control Laws: NDI and INDI

The model-based inverse feedback control method can consider the model and data, and provide a clean control-design framework environment; therefore, baseline control law of all kinds for verifiable aircraft used such methods. In this paper, we carried out the basic mathematical derivation of the two inverse system control methods, nonlinear dynamic inversion (NDI) and incremental nonlinear dynamic inversion (INDI) from nonlinear mathematical theory. We briefly analyzed the similarities and differences in stability and robustness of the two types of control methods in mathematical derivation, and simulated with the landing control law of carrier-based aircraft with two control methods. The results show the INDI compared to NDI have higher robustness, meanwhile, two types of inverse system control methods and conventional control methods can exist in the same design of the control mode, by the authority management, the inverse feedback design method can control the corresponding states of a specific control channel.

Fei Luo, Junhong Zhang, Biao Jiang

Analysis and Experimental Validation for a Simplified Flame Tube Subjected to Combined Thermal-Acoustic Loadings

Aiming for mastering the analytical techniques on the vibration response of metallic structures under combined thermal-acoustic loadings, a simplified flame tube was used for investigation, both on analytical process and experimental validation. The experiment was conducted under both the room temperature and an extreme temperature of about 450 ℃, and the analysis process based on finite element method (FEM) was developed and implemented in commercial FEM software, correspondingly. The analysis results were validated via experiment, and shows: 1) Under the room temperature, the analysis successfully got the modal frequencies of the flame tube, and the error of vibration response results is less than 15%; 2) The vibration response under thermal-acoustic loadings is highly effected by the temperature distribution, by specifying a supposed temperature distribution, the analysis results of both foundational frequency and vibration level was fitted with the experimental results within the error of less than 15%.

Hongwei Zhou, Liang Xie, Dingwen Guo, Kai Pan

Simulation and Test Study on CFRP with T-Shaped Stiffener

In the sense of mechanical properties, the new T-shaped integrated composite structure where the skin and the stiffener share the laminates, is quite different from the conventional one. In this paper, a simplified computational model is established from the perspective of stiffness property of the T-shaped integrated structure. First, in order to verify the accuracy of the computational model, modal test and simulation calculations are performed. Then, according to the comparisons of calculating results, a series of dynamic response tests of the integrated structure are carried out using acoustic apparatus which provide high-level load over 160 dB. Dynamic responses of the T-shaped integrated structure are measured using strain gauge during the process. The results of finite element analysis are in good agreement with the experimental results, which proves the validity of the computational model and the analytical method, and thus reveal its prospective industrial utilization.

Kun Yang, Sha Lin, Qun Yan

A Slider-Type Trim Strategy to Deal with Wing Perforation Damage Based on CFD

In this paper, a numerical simulation study is carried out on the aerodynamic characteristics of the aircraft wing surface after damage. The damage form is the wing perforation. To study the aerodynamic characteristics of the UAV under the condition of varying degrees of damage to the wings of the small airplane model, establish the geometric model of the airplane model in the CATIA 3D modeling software, and establish the geometric model in ANSYS ICEM and divide the calculation domain flow field grid. Perform aerodynamic calculations in ANSYS FLUENT. Firstly, the aerodynamic characteristics of the undamaged aircraft are calculated and analyzed, and then the aerodynamic characteristics of each damage situation are compared according to the different damage positions, and a response strategy using the slider as an auxiliary trim method is proposed. The research results have certain reference value for aircraft design of this type of layout.

Qiancheng Peng, Yang Pei, Mingsuo Li, Chunyu Bai, Yu Zhang

The Application of Improved Ant Colony Algorithm in the Optimal Design of Actuator Stiffness

The stiffness based design is more and more widely used in the development of civil aircraft actuators. The stiffness, strength, weight and other performance parameters restrict each other, so it is necessary to find a parameter optimization method to coordinate this constraint relationship. In this paper, based on the real coding and the traditional ant colony algorithm, the population diversity index is introduced, and the adaptive optimization of crossover probability and mutation probability is used to improve the global search ability of the ant colony algorithm with the idea of genetic algorithm. Taking the stiffness design of the piston of an actuator as an example, the improved ant colony algorithm of this paper is realized by MATLAB programming. The results show that the improved ant colony algorithm can find a group of solutions that meet the performance requirements, and the convergence speed and optimization ability of the algorithm are better than the traditional ant colony algorithm. Thus, a parameter optimization method for actuator stiffness optimization design is found.

Liu Peng, Dong Linyuan, Zhang Wei

Research on the Method to Formulate the Allowable Standard for Aero-Engine Labyrinth Seals Clearances

In order to formulate labyrinth seals clearances allowable standard to ensure the operation safety of aero-engine taking the realization of air system functions into concern, this paper put forward a method to formulate the allowable standard for labyrinth seals clearances on the basis of probabilistic analysis and surrogate modeling of functional parameter of internal air system. In this method, the key labyrinth seals of every functional parameter of internal air system could be recognized, and the corresponding allowable range for every functional parameter could be determined precisely. The aggregation of all the allowable ranges formulates the allowable standard. Through an internal air system case, the procedures of the proposed method are described concretely, and the allowable standard for the fourteen labyrinth seals clearance is obtained in terms of internal air system function realization, which demonstrates the value of proposed method in the production and repair of high-quality aero-engine. Moreover, the case gives concrete evidence that the labyrinth seals clearances allowable standard could be formulated exclusively for a certain aero-engine by the proposed method.

Chenxing Song, Yu Fan, Mingchun Deng, Ziyue Liu, Yi Shen

Application of Flight Test Data Mining in Safety Monitoring of Civil Aviation Products

Aiming at the problems of flight test data mining, studying on data added value and civil aviation product safety monitoring, by using of flight test data resources, considering flight test characteristics, and learning from foreign airworthiness related technical methods, the safety monitoring parameter system of flight test aviation products at different levels is established, for example, the different levels are airplane, configuration, key system, survivability equipment and flight test. Secondly, the more safety data of accident, accident symptom, using difficult, unsafe event, fault, utilization, flight intensity and so on are used for establishing parameter models. Finally, the warning value model of safety monitoring and safety trend analysis based Weibull are established。 It provides an effective method for the multi-parameter safety monitoring based on flight test data mining. At the same time, it provides technical support of safety trend prediction and comprehensive early warning.

Feimin Li

Analysis and Improvement on Asymmetrical Wear in Aircraft Bootstrap Reservoir

Aiming at the leakage failure and asymmetrical abrasion of a certain type bootstrap reservoir of aircraft, the analysis is carried out from the sealing type and supporting structure of the reservoir. Through comparison, it is known that under the same sealing type and sealing parameters, other similar components did not leak, so the failure is not caused by the sealing type and sealing parameters. From the perspective of the internal support, the bootstrap reservoir is a multi-nested structure, which requires high coaxiality of each component, and even over-constraint. The components is prone to generate additional load during operation and aggravate the wear of the sliding pair, including seals, high-pressure pistons, piston rods, etc. By enlarging the mating clearance, over-constraints of the internal matches are removed, the sliding pair wear in the high pressure cylinder is avoided, and the leakage failure of the bootstrap reservoir is eliminated. Considering that removing a constraint will influence the stiffness of the whole structure, vibration and impact tests have been carried out, and the new bootstrap reservoir has passed the tests.

Xiangrong Xu, Pengfei Zhang, Qinghe Zhou

Optimization of Design Method for Thermal Shrinkable Backup Ring in Aircraft Hydraulic Components

For the leakage failure caused by the damage of the rubber seal, the cause of the rubber ring damage is analyzed. Through the torsion and rapture of the rubber ring, the problem of thermal shrinkable poly tetrafluoroethylene (PTFE) backup ring heating over shrinkage is found. Finally, this failure is solved by optimizing the design method of the backup ring, including the reserved shrinkage, thickness compensation, etc.

Xiangrong Xu, Yibo Ge, Changming Li

Research on Fast Decision Method of Multi Target Attack Based on Improved AHP and Orthogonal Experiment

In the air to ground multi-target attack task, the attack sequence is an important factor of task completion rate and attacker survival rate. In order to solve the problem of target feature difference, the improved analytic hierarchy process (AHP) based on information entropy method is applied to solve the problem of target feature difference. By selecting the significant attributes of attack decision, the computation of the attack decision algorithm can be effectively reduced and the real-time performance of attack sequence decision can be improved. Aiming at the problem that the existing attack decision-making methods focus on correctness, the improved AHP and orthogonal experimental method are innovatively combined to improve the speed of the multi-target attack decision algorithm. Finally, based on the multi-target attack decision scheme, the artificial potential field method is applied to route planning. The simulation results show that the new method takes into account the correctness and real-time of decision-making.

Jiaju Wu, Xingjun Su, Yueming Zhao

The Design and Analysis of Airborne Hydraulic Hand Pump

The centralized filling subsystem is used for hydraulic ground service, in which the hand pump is the power component to complete the conversion of mechanical energy to hydraulic energy generated by manpower, thus realizing the purpose of injecting hydraulic fluid from the ground hydraulic fluid tank to the aircraft hydraulic reservoirs. In this paper, from the investigation of domestic and foreign typical civil aircraft filling maintenance method and hand pump data, comprehensive consideration and balance of its displacement, weight, installation size, operation force and mechanical efficiency and other key technical indicators, put forward a reasonable displacement and parking space, light weight, pretty mechanical efficiency of hand pump design scheme. It can greatly improve the efficiency of ground filling, reduce the burden of ground maintenance and save costs.

Heng Zhang, Changming Li, Zhen Wu

Generation and Verification of Flight Forbidden Area in Convective Weather Based on Real Data

The flight forbidden area (FFA) in convective weather is an important information resource for aviation. Using the density-based spatial clustering of applications with noise (DBSCAN), convex hull function in OpenCV library and other methods, the generation and verification of FFA in convective weather based on real weather and trajectory data are proposed in this study. Four relationship classes between flight trajectories and FFA are defined and eight examples are conducted to investigate the impact of radar reflectivity threshold and safety margin on the accuracy of FFA. Judging from the results, 40 dBZ is a better radar reflectivity threshold for the generation of FFA in convective weather, as the proportion of samples that fly outside of FFA with 40 dBZ is higher than that with 35 dBZ, and the proportion of samples that fly inside of FFA with 40 dBZ is lower than that with 35 dBZ. In addition, the accuracy of FFA decreases rapidly with the increasing of safety margin and it is suggested that the safety margin should range from 7 to 15 km to get a more realistic FFA.

Xi Chen, Zeyuan Liu, Yungang Tian, Jibo Huang, Hui Ding

Flight Dynamics Modeling and Simulation of Propeller Deflected Slipstream VTOL Aircraft

In this paper, the flight dynamic model of Vertical Take-Off and Landing (VTOL) aircraft which equips a propeller-wing-flap system that produces slipstream is established. The complete aircraft is modeled by combining experimental results, theoretical calculation, and empirical data. Firstly, the propeller deflected slipstream effects and the parameters of ducted fan are obtained by bench test. The DATCOM are used for generating the aerodynamic coefficients. Then, the 6-DoF nonlinear flight dynamic model in both hover and forward flight conditions are deducted by employing the assumption of linear superposition. The gyro effect and gravity are considered. Finally, specific trim conditions in hovering, transitional and level flight states are determined, and dynamic characteristics at trim are studied by both full model simulation and linear system analysis obtained through small-perturbation theory. It is found that the aircraft is critically stable in hovering condition. The damping ratio of short-period mode is relatively small, and the phugoid mode divergence in the transition state. The aircraft is less well damped in the level flight condition. The built model accurately reflects the dynamic characteristics of the VTOL aircraft and provides help for the design of the flight control system afterward.

Sijia Jia, Zhenkai Zhang, Weijun Wang, Chao Yang

The Shock Response Spectrum Study Based on Gunfire Signal

Some gunfire environment can be depicted as a repeated shock or transient vibration environment, which is generally described by one impulse signal. In recent years, the Shock Response Spectrum (SRS) is widely used because it not only describes the shock excitation signal, but also the structural dynamic characteristics. In this paper, based on one finite element model of a certain aircraft loaded with aerial guns, different gunfire responses were analysed and classified. For the unsteady gunfire environment, the frequency domain of it can be depicted by the SRS. Two conversion methods from the time domain response to the frequency domain SRS, which were the Digital Filtering Method and the Motion Differential Equation Method, were introduced in detail. The SRS obtained by two methods were basically the same, which meant the two methods were verified mutually. At last, the standard spectrum of the SRS was obtained. All of the work provides a universal analysis method for the SRS study in engineering filed.

Yixuan Li, Jijun Liu, Kaixiang Li

Research on Fault Detection Technology of Air-to-Air Missile Based on Data Mining

According to the research experience of air-to-air missile testing, the occurences of some product faults are of low frequency and sporadic, and the fault features usually hide in the details of testing signals. However, the conventional rule-based fault detection methods are difficult to issue early warning against these product faults. In order to solve the problems of miss-detection faced by the conventional missile fault detection methods, this paper started from studying the data feature extraction, feature space construction, and automatic data mining, and carried out the research on engineering application of the data-driven fault detection technology. In view of the complexity of missile test data, the feature extraction of missile test data was achieved with the applications of mathematical statistics, clustering, artificial intelligence, image feature extraction, defining a method of missile fault detection based on the $$3\sigma$$ 3 σ criterion, and a data-mining based fault diagnosis system was developed with the ability to evaluate product quality on the foundation of historical missile test data.

Hao Cui, Jun Yan, Pengpeng Zhang, Dongsheng Yang, Zhiguang Chen

Information Extraction of the Aerodrome Hazardous Weather Warning via Deep Learning

The bad weather would affect the operation of airport. Improving capability of weather information detection can guarantee efficient operation of airport. Some air traffic management systems are able to extract the weather information from the radar signal. Some kinds of text include weather information during actual operations, such as aerodrome hazardous weather warning. Current ATM systems cannot process texts due to unstructured characteristics. Compared with radar signal, the aerodrome hazardous weather warning consists of human’s prior experience, which is more useful in application of situation awareness. This paper proposes a deep-learning approach for weather information extraction, which can improve the capacity of aerodrome hazardous weather warning information extraction. The method applies the named entity recognition model to extract the information such as weather type, weather state, speed and direction of wind, starting and end time, etc.

Xuan Wang, Hui Ding, Jibo Huang, Qiucheng Xu

Aerodynamic Characteristics Analysis of Refueling Drogue Under the Influence of Bow Wave Effect Based on Patched Grid Technology

Air refueling technology has become one of the essential guarantees of modern air transportation and combat effectiveness. However, in the docking stage of aerial refueling missions, the drogue and hose often deviate from the original position due to the influence of the bow wave effect of the receiver during air refueling, thus the accuracy of docking of the probe will be significantly affected. In the present work, aerodynamic disturbance around the drogue due to the existence of receiver in size of typical fighter aircraft is studied by the CFD simulation method. In order to balance computational efficiency and accuracy, the surface patched grid technology is employed in the CFD simulation. The influence of the drogue with relative distance angle of attack of the receiver is further analyzed. When the receiver is close enough, disturbance of side and vertical force on the drogue could be at level of 100 N in the selected case. Therefore, study the dynamic response and control method of the drogue under the influence of the bow wave effect is essential.

Wangyi Zhou, Qian Zhao, Xiheng Zang, Qingsong Liu, Lei Qiao, Junqiang Bai, Quanlin Qi

Analysis on Shrinkage of Sleeve at the Control Piston Section of a Solenoid Valve

The smoothness of the movement of solenoid valve is highly related to the clearance. When the clearance is large, the opening and closing of the solenoid valve is smooth, but the leakage will increase; when the clearance is small, the leakage is reduced, but the solenoid valve may be stuck when it opens or closes. In addition, under higher pressure, when the valve sleeve is compressed, the clearance between the valve core and the valve sleeve will be reduced, which will affect the opening and closing performance of the solenoid valve. This paper analyzes the shrinkage of the valve sleeve in the operating piston section of a certain type of solenoid valve, compares the calculation and simulation results, and obtains the shrinkage of the valve sleeve, which provides support for improving the opening and closing performance of the solenoid valve.

Dai Pengbin, Yang haili, Li Changming

Structure Design and Analysis of Reservoir Fill Selector Valve in Civil Aircraft

The hydraulic system of modern airliners may leak out of the system. So it is necessary to regularly refill and maintain the hydraulic system on the ground. The operation is complicated and inefficient. In this paper, the structure design and analysis of the reservoir fill selector valve in the integration filling system are carried out. Study the structure characteristics, advantages and disadvantages of foreign valves. The comparative analysis is made from the aspects of weight, size, cost, life and leakage. The structure is optimized based on the E-type valve. The leakage of the new valve structure is calculated and verified to meet the system requirements, which can be used as the structural model of the domestic aircraft integration filling system reservoir fill selector valve.

Xiaofeng Chen, Changmin Li

Transition Flight Demonstration of a Quin Tilt-Rotor UAV in the Low Speed Wind Tunnel

A quin tilt-rotor (QuinTR) aircraft, equipped with five convertible rotors from vertical to level and vice versa, is one of the most promising Unmanned Aerial Vehicle (UAV) configurations combing the hovering capabilities with the high-speed cruise performance. However, the process of transition flight is quite challenging due to the significant changes in aerodynamic and propulsion characteristics, and therefore requires a tilt-conversion corridor and gain-scheduled flight controller. This paper presents recent advances in the project: transition flight control design and demonstration of a QuinTR UAV in the low speed wind tunnel at the China Aerodynamics Research and Development Center (CARDC). Based on the wind tunnel test benchmark, a prototype QuinTR UAV model has been constructed for both essential aerodynamic and virtual flight tests, a six-degree-of-freedom dynamics model covering the full conversion process has been developed for control law design and simulation, and a virtual flight test has been carried out for successful demonstration and validation of the transition flight.

Nie Bowen, Yang Hongsen, Guo Tianhao, Ren Zhongcai, Liu Zhitao

Analysis of Aircraft Fuel Thermal Management System Under Different Architectures

The increasing number and power of electronic equipment on the aircraft causes a large amount of heat loss inside the aircraft. It is particularly important to conduct a reasonable thermal analysis on the aircraft. In this paper, four architectures of fuel thermal management system are proposed and analyzed. The difference among these four architectures is the flow directions of the fuel. The mass conservation and energy analysis are carried out for different parts of the four structures, and the differential equations of mass and energy are established. The heated fuel temperature and the fuel mass flow rate are the focuses. The variation of the heated fuel temperature of four architectures is calculated under fixed flight conditions. Under different flight conditions, the variation law of fuel mass flow with the flow parameters in the four architectures is analyzed with the value of the heated fuel temperature satisfying 421. The results show that only the dual-tank architecture with fuel recirculation split into 2 parts can meet the requirements under different flight conditions.

Zhao Qian, Pei Yang, Ge Yuxue, Li Wan

The Research on Net Takeoff Flight Path Calculation Method Based on Gross Flight Path Under Complicated Condition

In the operations at high elevation/complex terrain airport, to comply with the one engine inoperative take off flight path obstacle clearance requirement, the whole net takeoff flight path which often last over hundreds of kilometers need to be constructed, the key segment is the net third segment. At present, the manufacture’s performance software, include Boeing and Airbus, can only export the net third segment data in standard second segment and straight out departure condition. for more complicated operation condition, such as extended second segment, turn and its mix departure, it has not net third segment data. In this paper, a new climb gradient acceleration rate method to calculate the net third segment is proposed, which is based on the gross flight path data calculated by manufacture’s trajectory simulation performance software, and can handles the complicated operation conditions mentioned early. Take B737-700 for example, the different result are compared using manufacture’s performance software, a simplified method and the new climb gradient acceleration rate method. The results show the new method has better precision than existing simplified method, and can show the regulation compliance in the one engine inoperative take off under complicated operation.

Yu Jiang, Zhu Wenlong

Correlation Between Processing Parameters and Behavior of Chromium Diffusion Coatings on Nickel-Based Superalloys: A Review

This study reviews the current understanding and research on the methods and performance of chromium diffusion coatings on nickel superalloys. Chromizing has been considered as an effective approach to improving the resistance to hot corrosion, especially type II hot corrosion, and the results from the literature shows that the different concentration of chromium in different types of nickel-based superalloys influence the coatings morphology and properties. Moreover, various methods have been developed to chromium diffusion coatings and the selection of method is not only dependent on processing temperature and time but also on the substrate in matter. Through the experimental results obtained by various researchers, the dependencies between coating deposition methods, process variables, and microstructure and surface properties of chromium diffusion coatings on nickel-based superalloys are discussed. Finally, the future research direction is pointed out.

Jian Chang, Yahong Li, Hai Shi, Limin Sun, Yang Cui

Noise Characteristics Contrastive Analysis of Dual Synthetic Jets Actuator and Synthetic Jet Actuator

Dual synthetic jets actuator (DSJA) has great potential application in airfoil separation flow control, jet vector control, heat dissipation and other aspects. However, DSJA can make noise of more than 80 dB under the optimal working frequency, which is very unfavorable for the application of DSJA in practical engineering. For the purpose of improving the performance of DSJA. It is important to study its noise characteristics in order for the noise reduction in the later stage. In this paper, DJSA is compared with synthetic jet actuator (SJA) in a series of acoustic experiments by using the multi-point response test method. For both two actors, the changes of sound pressure level and wind speed under different driving frequencies are studied. What’s more, the distribution laws of sound pressure level are analyzed at different measuring distances and angles. In addition, the spectral characteristics at different measuring distances are also discussed. Experiment results indicate that both the sound pressure level and the wind speed of these two actuators increase first and then decrease with the change of the driving frequency. However, under the same working frequency, DSJA makes a lower noise than SJA and produces a stronger directivity in the export orientation. Finally, there are few changes in the sound pressure level of the noise in the far field.

Wu Pan, Luo Zhenbing, Peng Wenqiang, Zheng Mu, Kang Ying

Multivariable Control and Robustness Analysis of Supersonic Aero-Engine Based on ADRC

Modern advanced aeroengine has a wide range of work envelope. To solve the problem of supersonic aero-engine multivariable and robust control, this paper analyzes Active Disturbance Rejection Control (ADRC) controller in acceleration and deceleration process and switching afterburner state under three typical working conditions, the settling time and overshoot of ADRC control are comprehensively analyzed under the full flight envelope, the influence of the disturbance of the fan/compressor guide vane angle and the inlet ramp angle is also analyzed. The results show that the ADRC controller can realize the “zero error” following control of Nh and NPC under three typical working conditions, non-controlled parameters work in the normal range, while the NPC control loop fluctuates greatly and jumps violently under the switching afterburner state. ADRC controller can achieve stable control in the whole envelope. The response speed of NPR control loop is slightly faster than that of Nh control loop, but the overshoot is larger at high altitude, while the overshoot of Nh control loop is very small. ADRC controller can resist small disturbance of fan/compressor guide vane angle and inlet ramp angle under switching afterburner state and has good robust performance.

Chen Wang, Lu Ai, Xian Du, Ximing Sun

Guidance Information Estimation for Strapdown Imaging Seeker of Tactical Missile Guided by Optimal Guidance Law

Strapdown imaging seeker has the advantages of high reliability and simple structure. The major disadvantage is that inertial line of sight rate is not directly available for the implementation of proportional navigation, and the uncertainty of seeker scale factor inevitably produces a parasite loop which severely degrades guidance performance. In this paper, a guidance system model of strapdown imaging seeker based on optimal guidance law (OGL) is constructed. The wide field of view of seeker results in nonlinearity of measurement equations, so an extended Kalman filter (EKF) algorithm is proposed to estimate the target state information required by OGL. The seeker scale factor error is estimated and compensated in the proposed algorithm. Numerical simulation results show that the EKF algorithm can estimate guidance information and scale factor error when the seeker scale factor is considered in the measurement equations. The influence of parasitic loop coupling on guidance system can be eliminated by compensating scale factor error of seeker, and the stability and precision of guidance system can be improved.

Qi Wang, Zhizhong Liao, Fei Yan

Simulation Study on the Influence of Rocket Tail Flame of Ejection Seat on the Thermal Flow Field in Engine Room

This paper proposes a simulation method and technology for the effect of the ejection seat rocket pack tail flame on the heat flow field of the engine room under the multi-seat ejection condition, combines the six-degree-of-freedom motion model of the ejection seat with the CFD numerical simulation method to realize the simulation process of the thermal flow field in the engine room according to the working mechanism of the seat. The motion trajectory and attitude change law of the first ejected seat under different ejection conditions is calculated by a program written in C#, the movement of the human-seat system and the rocket at the boundary in FLUENT is specified with UDF, then the temperature and pressure change law of the second ejected seat, occupant and the surface of the cockpit during a side ejection at different ejection speeds are simulated. The simulation results show that the temperature of different characteristic points in the engine room rises first and then decreases after the rocket package is working, reaching a peak at about 60ms. The temperature at the back of the seat is the highest, and the temperature in the engine room drops faster while the pressure peak is lower when the seat is ejected at a certain speed. The analysis results can provide a theoretical basis for the design and verification of occupant thermal protection equipment.

Lou Jin, Yibin Wu, Liang Wu, Dongyue Cui, Pin Yang

Analysis on Over-leakage of a Solenoid Valve

Aiming at the fault of over-leakage of a certain type solenoid valve, influence of the total leakage is studied based on the formula of annular gap flow. Firstly, internal leakage ways of the solenoid valve under the power-on and power-off conditions are analyzed. Secondly, factors affecting overlap of the key valve port are explored, including the axial dimension tolerance of the spool and the sleeve, and size of the compensating groove of the spool. Finally, improvement measures are obtained, including changing the axial dimension tolerance of valve rand from symmetrical tolerance (±0.1 mm) into positive tolerance (0, + 0.2 mm), and widening the distance between the control edge and the compensating groove. The improvement measures eliminated the fault of excessive leakage of solenoid valve.

Yibo Ge, Yihao Du, Changming Li

Fretting Fatigue Crack Monitoring in Aero-Engine Turbine Tenon Connection Structure Using Silicon Based Replica Method

Fretting is a phenomenon which appears when a contact between two parts is subjected to micro-movements. Fretting fatigue is of great concern for the aerospace industry, especially for the blade/disc tenon connection structure. In this paper the jet engine turbine tenon connection of DD6/FGH96 material pair is studied, and the simplified specimens are designed and machined. The fretting fatigue experiments are carried out with different temperature and load levels. To monitor the fretting fatigue crack propagating, the silicon-rubber replica method and telephoto microscope are used for experiments both at room temperature and high temperature of 600 ℃, respectively. The testing results show significant difference of the fretting fatigue life of DD6 single-crystal super alloy between conditions of high and room temperature. The fretting fatigue crack initiation site/orientation and length are obtained from microphotograph data of the silicon rubber replicas and then analyzed. The silicon-based replica method is proved to be an effective technique for monitoring the propagation of the fretting fatigue crack.

Kai Sun, Rui Zhang, Yihan Xu, Naixian Hou, Xianghui Meng

Effect of Different Scanning Modes and Heat Treatment on Microstructure and Mechanical Properties of GH4169 Manufactured by Selective Laser Melting

GH4169 superalloy was prepared by selective laser melting technique. The samples were obtained by scanning in a single direction per layer and scanning in a 90° direction per layer, respectively. The microstructure and precipitated phase were compared and analyzed by OM, SEM and EDS to investigate the non-equilibrium microstructure characteristics and the influence mechanism on mechanical properties of laser additive manufacturing materials of GH4169 under three heat treatment systems. The results show that in the X direction of laser scanning deposition, the tensile strength at room temperature of the material with the same scanning direction of each layer is 4.5% higher than that of the material with the scanning direction of 90°, and the reduction of area is 75.6% higher. After solution and aging treatment, δ phase was precipitated and Laves phase was partially dissolved, but the element segregation in the remelting zone between the cladding layers was not completely eliminated. Homogenization treatment at 1050 ℃ for 1h promotes uniform distribution of segregation elements in cladding layer, remelting layer and dendrite. After homogenization treatment at 1100 ℃ for 1h, Laves phase was fully redissolved, and δ phase and strengthening phase γ ‘ were precipitated again after solution and aging. After heat treatment, the tensile strength at room temperature of the samples prepared by the two laser scanning methods is basically the same in the X direction.

Jingyi Zhou, Zhenwei Wei, Siyi Tang, Wenxia Zhao, Shaoqing Guo, Jian Wang, Zijun Zhao

Research on Airworthiness Qualification Test Technology of Radiation Emission in Civil Aircraft Flight Control Electronic System

It is the first time that domestic civil large aircraft has been developed, which lacks the technical experience of airborne system-level airworthiness qualification, and the research of radiation emission at home and abroad is mainly based on simulation evaluation, while the simulation results are used only as a reference in the airworthiness qualification process and cannot be used as evidence of conformity. And there is little airworthiness test experience on complex system-level. In this paper, taking civil aircraft flight control electronic system as an example, through the demonstration of the airworthiness requirement, the description of the complexity of civil aircraft flight control electronic system, demonstrate the airworthiness qualification test and optimization process, providing experience for the airworthiness qualification of civil aircraft complex system. The results show that the radiation emission of flight control electronic system is greatly affected by the system environment, and it is necessary to consider the test setup layout and show the system compliance to the DO-160G requirements.

Lu Kuan, Li Aijun, Wang Tianbo, Li Linxiao, Wang Jianyuan

A Intelligent Cabin Design Based on Aviation Internet of Things

The advanced cabin system can greatly affect the passenger experience and cabin management efficiency, and is an important means for airlines to improve their service quality and brand strategy and implement differentiated competition. Intelligent cabin based on IoT can realize intelligent interaction, provide passengers with integrated experience and active one-stop service, and make passengers' flight a pleasure. At the same time, it can change the traditional service model and improve the efficiency of airline services. In this paper, the application scenarios of aviation IoT smart cabin are analyzed, a smart cabin architecture based on aviation IoT is designed, and solutions for upgrading the existing civil aircraft cabin are provided.

Jue Wang, Jianfeng Feng, Yijia Gao, Xin Jiang, Jian Tang

An Inertial Information Based Image Stabilization Method for Airborne Hybrid Strap-Down Inertial/Celestial Integrated Navigation System

The precision of star sensor is usually influenced by the carrier dynamic. In this work, a hybrid strap-down inertial/celestial integrated navigation system is raised. The inertial measurement unit is integrated installation with the star sensor, which ensures the attitude variation of the star sensor could be indiscriminately acquired. Then the star images are shifted and rotated according to the inertial information. Consequently, the star image stabilization is achieved. The experiment results demonstrates that the standard variance of the star centroid coordinates after stabilization is about 0.1 pixel for both uniform angular motion and sine angular motion when the average velocity is less than 3 °/S. The approach provided can significantly enhance the dynamic adaptation and effectively improve the detection capacity for the star sensor. It shows compact structure, small volume, light weight and offers a possible solution for the contradiction between high precision and miniaturization in airborne star sensor, which has positive guiding significance for engineering application of airborne integrated navigation system.

Chen Pu, Hu Xiaodong, Ding Xiaokun, Liang Ke, Wei Qing

A New GNSS Aided Strapdown INS Dynamic Coarse Alignment Algorithm

According to the requirement of dynamic coarse alignment of moving base, a new inertial navigation coarse alignment algorithm assisted by satellite velocity information is presented. A simplified alignment model of linearized Kalman filter with large azimuth misalignment is obtained by adjusting the inertial solution scheme and de-fining a new form of velocity error model. The offline simulation results of the actual test flight verify the effectiveness of the method. The horizontal attitude error of coarse alignment in 120s is no more than 2°, and the heading error is no more than 5°, which can meet the initial hypothesis requirements of the subsequent fine alignment filter for the small-angle linearization model.

Guo-Da Cheng, Guo-Liang Yang, Jia-He Xia, Yang Shang, Sihai Li

Optimization of Condition-Based Maintenance Strategy for Stochastic and Continuous Deteriorating Systems

The paper focuses on modeling of a periodic inspection condition-based maintenance strategy for stochastic and continuous deteriorating single-unit systems. We consider the system's stochastic deteriorating process is Gamma Process and three types of maintenance including preventive maintenance, preventive replacement and corrective replacement. Preventive maintenance is imperfect maintenance which improves the deteriorating state of system randomly. Imperfect maintenance time is related to maintenance effectiveness. Preventive replacement and corrective replacement are perfect maintenance which makes systems as good as new. The object is to find the maintenance strategy which availability of the system limited by cost in a finite horizon is optimal and variables of maintenance strategy are inspection interval, preventive maintenance threshold and preventive maintenance times threshold. As a result, a simulation model based on Monte Carlo is developed and a numerical example is introduced.

Yukui Zhu, Xiang Cao, Jian Dong, Mengke Fu

Design of Flight Performance Calculation Component for UAV Mission Planning Based on Performance Data Package

The UAV mission planning performance calculation component is part of the mission planning system of common ground station, it can provide basic data for conflict detection and mission rehearsal during mission planning, and help mission planners understand and check the compatibility of mission routes with aircraft performance, mission safety and expected performance state. This paper designs and develops a common flight performance calculation software component compatible with the “UAV Common Mission Planning System”. It is designed to obtain aircraft information and performance parameters of each flight phase through interpolating the UAV performance data package. After replacing the aircraft performance data package, it can meet the mission planning performance calculations of other types of aircraft, at the same time, the performance component performs well in terms of calculation time, calculation accuracy, and consumption of computer physical resources. This paper describes the performance calculation component from the perspective of software design, software implementation and software testing.

Huan Xie, Yiheng Pan, Rui Li, Chuyun Huang, Linmin Yan, Rui Han, Tao Li, Bin Xia

Design and Implementation of a Key-Erase Control System

Faced with the need for the security of airborne confidential information in a complex situation, a design method of the key-erase control system is proposed, and the design ideas of the key function modules and the key-erase control logic algorithm of the system are analyzed and explained. At the same time, a self-checking method for key-erase circuit is designed. The design method of the key-erase control system described in this paper is more intelligent and effective than the existing key-erase control system of aircraft, and can avoid the occurrence of spurious triggering key-erase and key-erase failure to a greater extent.

Yinghao Wei, Bingqiang Li, Qing Zhang

Application and Promotion Strategy of Beidou Airborne System in Civil Aviation Transport Aircraft

Beidou system has been widely used in mapping, forestry and many other civil fields. Due to the high security level, high international standards and high technical barriers in the field of civil aviation transportation, Beidou satellite navigation system has not been fully applied in the field of civil aviation transportation. Based on the analysis of the relevant policies of Beidou System in civil aviation application, this paper puts forward the promotion strategy of Beidou airborne system in civil aviation transportation industry, which is “from easy to difficult, first carrying then integrating, first domestic aircraft then industrial application”, and discusses the detailed application path in two application stages, namely tracking and navigation. Accelerate the localization process of civil aviation aircraft satellite navigation system, realize the independent control of China's civil aviation aircraft satellite navigation source, drive the industrialization and large-scale application of Beidou in China's civil aviation field, and jointly promote the landing and blossoming of Beidou satellite navigation system in the civil aviation field.

Jue Wang, Zhan Zhang, Yijia Gao, Jiuyuan Guo, Yaying Hu

Research on the Propagation Characteristics of Millimeter Wave Signals in Complicated Enclosed Spaces

This paper aims at simulating the electromagnetic environment inside an enclosed chamber with high conductivity and complicated structure, validating the feasibility of high-speed wireless communications inside aircraft cabins. It first built a characteristic model which represents the propagation scenario of an aircraft component, then simulated the propagation of 77 GHz millimeter wave source through ray tracing method and obtained wireless channel model including power distribution characteristics and delay spread model. Simulated results demonstrated a feature of standing wave distribution inside the structure, and a relatively large attenuation for millimeter wave propagation in such environment. Delay spread is normally less than 10 ns, with a typical characteristic of clustering. It proved that wireless communication at millimeter wave band in such configurations requires necessary channel coding technology to guarantee data transmission rate and system reliability.

Shaoqing Zhang, Liang Zhang, Yi Lu, Tongyu Ding

Verification Matrix Applied During Verification Process of Airborne Software

Activities during software verification process take more than 60% effort among entire life cycle and verification credit could be taken at various levels. Insufficient requirement-based verification may not identify the software defect completely, which leads to lower software quality, also in most cases, the tracking document only includes the relation between requirement identification ID and verification ID, which could not show whole picture of the verification work. Although verification matrix is not mentioned in DO-178B/C, ARP-4754A has corresponding sections to describe it, so it is considered that verification matrix can be applied in software verification process with reference to ARP-4754A, additionally, other attributes of software can be added to this matrix. In this article, combined with engineering experience, necessity to apply verification matrix during software verification process has demonstrated, also, instruction of how to use verification matrix has described, the benefits gained from the project has concluded.

Yuan Liu, Qing Guo, Wen Liu, Rui Wang, Ding Zhao

The Applications of the PHM in INS Area

PHM is an effective technique of which can advance the capability of the colligating Fault Diagnosis and reduce the use and the RMS (Reliability maintainability Security) fee of the government equipment. By absorbing the advanced overseas experience, PHM is embedded researched. It is combined the idiographic points of INS, and confirmed frame of PHM. The INS fault prognosis model which is based on PHM is proposed in the paper. It is detailedly expatiated on the INS PHM method, and take an example about the key circuits in INS to explain the scenario of the PHM. At last, it is expatiated the manage points about PHM in INS area. By the applications of the system, it is a large right-about change about the INS (Inertia navigation system) maintenance methods, viz. from the traditional Diagnosis method which based on the sensor to the prognosis method which based on the intellectualized system and from the afterwards or time-lapse maintain to the maintain method which based on the state maintain.

Wang Hanping, Lian Xiaotang, Liu Zhao

Research on Application of Satellite Navigation Airborne Equipment and International Standardization

The BeiDou satellite navigation system (BDS) has achieved global networking. It is an important means to improve the safety of air navigation and service quality by using BDS civil aviation airborne equipment. The path of BDS positioning and tracking equipment to achieve civil aviation application through airworthiness certification is analyzed. Research on BDS civil aviation industry international standardization and equipment development is carried out, laying the foundation for the civil aviation application of BDS airborne navigation equipment.

Zhan Zhang, Zhe Fan, Yaying Hu, Boyuan Gong

Research on Optimization of Docking Assembly Process of Large Airliner Mid Fuselage

Aircraft assembly, as the main component of aircraft manufacturing, bears the capacity of 40%–50% of the whole machine manufacturing. Among them, aircraft unit assembly is a powerful guarantee of aircraft quality, flight safety, cost and delivery cycle. The main characteristics of unit assembly are large size of parts, easy deformation of sheet metal parts or composite parts, complex assembly process, etc., which will produce assembly clearance or interference and other out-of-tolerance problems, especially in the unit joint area. In order to solve the above problems, SACC optimizes the unit assembly docking process of the mid fuselage in certain large airliner. This paper first introduces the status of the gap or interference in aircraft assembly, and investigates the main technical reasons and strategies. Secondly, combining with the situation of assembly in mid fuselage, from the aspects of assembly datum, unit precision and process allowance optimization and using the assembly tolerance analysis and the method for theoretical calculation of dimension chain, SACC finally realizes the breakthrough in mid fuselage assembly problems and efficiency. A solid foundation has been laid for improvement of customer satisfaction and meeting the delivery orders.

Yang Wubing, Liu Min, Fang Mengtai


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