Proceedings of the 6th China Aeronautical Science and Technology Conference

The unknown vibration has a significant negative effect on the engineering structure health. Therefore, it is necessary to predict the vibration response of the structure accurately. However, the existing vibration response prediction models have some problems, such as too much freedom, difficult sensor optimization and low prediction accuracy. To overcome these shortcomings, we propose a method based on Independently Interpretable Lasso and linear regression (IILasso-LR) to optimize sensor layout for response prediction. IILasso-LR more aggressively induces the sparsity of the active variables and reduces the correlations among them. Hence, we can independently interpret the effects of the selected sensor on the response prediction. In addition, the optimized sensor is used for response prediction, which greatly improves the efficiency of prediction. Experiments of finite element model is used to validate the effectiveness and accuracy of IILasso-LR. Effects of sensor location, number of sensors, excitation type and noise level are studied in detail. The results show that the IILasso-LR could predict vibration response effectively and satisfy industrial requirements.

The end-to-end orientation estimation method based on Convolutional Neural Networks (CNN) is proposed for non-cooperative situations where aircraft can’t send information to each other. In this paper, ResNet50 is used as the backbone network, using Euler angles and quaternions as labels to train the network. The dataset used to train CNN is generated through 3Dmax. The experimental results show that the orientation estimation of non-cooperative aircraft can be achieved through regression method, and it has high orientation estimation accuracy. The orientation estimation accuracy using two labels is compared. The minimum standard deviation of pitch angle, yaw angle and roll angle error is 2.005°, 1.117° and 2.012° respectively, and the minimum mean absolute error is 1.369°, 0.917° and 1.428° respectively. The minimum standard deviation of quaternion rotation angle is 0.375°, and the minimum mean absolute error is 1.292°.

The integrated design of the refueling device and the unmanned tanker is one key factor in the autonomous aerial refueling technology, which affecting the overall refueling performance. Starting from the design parameters of tankers and aerial refueling devices, the design parameters with high correlation were selected as the sensitivity analysis objects. The parameter sensitivity analysis of the selected design parameters was carried out by using the multi-parameter sensitivity analysis method, and the influence of parameters on the performance of the unmanned tanker platform was discussed. The results show that the empty weight coefficient and maximum external fuel supply have significant effects on platform performance and refueling capacity, and the comprehensive sensitivity is higher. The cruising speed and weight of the refueling device have a greater influence on the overall performance and have high sensitivity; Refueling hoses/boom length parameters have the lowest sensitivity. The conclusion can provide a direction for the future design of the refueling device, and also provide a reference for the integrated trade-off design of the refueling device and the tanker.

The cooperation of multiple UVAs can break through the limitation of single individual ability and improve the efficiency of mission execution. When executing large-scale tasks, the UAVs communication features, task time window and resource requirements all pose significant challenges to the collaborative task allocation algorithm. To effectively tackle the above problem, an optimization model of cooperative task allocation of heterogeneous UAVs with multiple constraints is established to meet the goal of minimizing task execution time while completing all tasks. On the basis, considering the complexity and scale-sensitivity of cooperative task allocation problem, an improved genetic algorithm is devised to solve the above model. The matrix encoded chromosome designed in our algorithm can naturally represent the resource consumption and task execution status of UAVs. Equipped with problem-specific operators, the proposed algorithm could achieve a good trade-off between the population diversity and convergence. The sufficient experimental data verify that the marked performance of our algorithm.

The main valve of a certain type of solenoid valve is a slide valve. The opening and closing of the valve is controlled by the electromagnet. The performance of the solenoid valve has strict requirements about leakage. The key factor of valve leakage is that the clearance between the valve core and the valve sleeve. If the clearance between the valve core and the valve sleeve is too small, the leakage can be reduced, but the valve became jam easily; if the clearance between the valve core and the valve sleeve is too large, the valve opens and closes smoothly without jam, but the leakage increases. Based on the electromagnetic reversing valve pair, an in-depth analysis of the clearance between the valve core and the valve sleeve is carried out. Under the condition of ensuring that the entire valve is opened and closed without jamming, combined with the maximum leakage required by the product, the minimum and maximum value of the clearance between the valve core and the valve sleeve is given by a series of analyses and experiments.

In this paper, the microstructures were studied by OM and SEM, and the tensile and stress rupture properties were tested for K465 superalloy casted by surface grain refinement and conventional technology. The results showed that: Compared to conventional casting, the surface grain size was refined from M-4 to M-9; The secondary dendrite spacing and eutectic content decreased, while the carbide content decreased from 6.18% to 4.36%; The volume fraction of γ′ had no change, the size of γ′ reduced both in core- and inter-dendritic region, and the homogeneity of microstructure improved; The room tensile strength and plasticity both improved. The medium-temperature stress rupture property improved significantly (800 ℃/600MPa), and the high-temperature stress rupture property decreased (975 ℃/225 MPa), which still met the specification. The change of mechanical properties is due to the refinement of the structure.

With the development of electronic technology and the increasing demand for complex tasks, large aircraft have the trend of complicated airborne systems, increasing number of sensors and decentralized information, resulting in a large number of alarm signals and a delay in crew response. The warning system can locate the fault source, comprehensively handle multiple conflicting warning signals or announcements, so as to assist the crew to make effective decisions and improve the safety and reliability of the aircraft. Based on the research of advanced Boeing and Airbus aircraft warning systems, this paper proposes a set of large aircraft warning principles and display technologies, including alarm priority design, alarm principal design, alarm display design and integrated alarm suppression design, which provides support for the development of large aircraft warning systems.

In the takeoff process of flying wing Unmanned Aerial Vehicle (UAV), the thrust line is higher than the reference position of the center of gravity and the landing gear is opened, which will produce a large nose-down pitching moment. When using the conventional control surface allocation configuration, the elevator needs to deflect a larger angle to offset this part of moment and make the aircraft climb according to the target pitch angle. A flying wing UAV takeoff control strategy with embedded control surface compensation was designed to resolve this issue. During the flying wing UAV takeoff, the embedded rudder deflection was used to offset the nose-down pitching moment. The calculation of the Attainable Moment Subset (AMS) showed that this method can significantly improve the range of aircraft control moment, and the feasibility was verified through flight experiments. It can improve the aircraft's pitch control ability and improve the actual climbing effect.

This article used the CFX method to study the circumferential flow and heat transfer characteristics of the anti icing flow path in the inlet casing under typical icing conditions. It explored the distribution of anti icing hot gas flow characteristics and the uniformity of heat transfer along the circumferential flow, and obtained the flow and heat transfer characteristics of key positions in the anti icing system. The calculation results indicate that under the calculation conditions, the hot gas velocity and temperature in the gas collection chamber exhibit a circumferential symmetric trend, and decrease along the circumference. The distribution of hot gas velocity and temperature in the blade is symmetrical along the circumference, and the velocity increases along the circumference, while the temperature is opposite. The inlet flow rate of the blades increases along the circumference, and the blade with the highest inlet flow rate is located at 180 degrees along the circumference of the hot air inlet of the inlet casing. In addition, the temperature of the hot air at the inlet of each blade decreases along the circumference.The velocity and temperature of hot air inside the cone exhibit an axisymmetric trend along the circumference.

The low order equivalent matching method is one of the important means to study the flight quality of complex high-order aircraft models. Low order equivalent matching methods are usually divided into frequency domain matching method and time domain matching method. The frequency domain matching method requires obtaining the model or frequency domain response of higher order systems and cannot process aircraft data. The time domain matching method requires processing a large amount of data and has low operational efficiency. By combining frequency-domain matching and time-domain matching methods, a low-order equivalent matching method based on parameter identification mixing time-domain and frequency-domain is proposed. The one-step least squares finished algorithm is used to extract the transitional lower order model from aircraft operation data in the time domain, and then the frequency-domain matching method is applied to identify the parameters of the lower order equivalent model from the transitional lower order model. Simulation shows that this method does not rely on the setting of initial values and parameter ranges, and can improve the simulation efficiency of the time-domain equivalent matching method by nearly ten times without losing accuracy. The results indicate that the low order equivalent matching method based on parameter identification mixing time-domain and frequency-domain is effective when applied to parameter identification of low order models.

Turbine disk cavity system is of great importance for improving the rotating turbine blades cooling efficiency and preventing gas invasion. This study focuses on turbine disk cavity characteristics at high-speed rotational conditions due to complicated flow and heat transfer mechanisms. Then, a novelty method is proposed to reveal multiple similarity criterion numbers of rotor-stator disk cavity between actual engine and experimental case conditions, based on the dimensionless analysis. Especially, a new evaluation standard including the dimensionless adiabatic wall temperature and dimensionless heat flux is put forward and proved to be equally important with the Nusselt number. Results show that the dimensionless heat flux in the turbine disk cavity mainly depends on Reynolds number and Mach number, while the dimensionless adiabatic wall temperature is dominated only by the same Mach number. When only Reynolds numbers or Mach numbers are considered, the relative error can reach 14.5% on the similarity of dimensionless heat flux. Therefore, this study can provide a theoretical method and engineering application to obtain flow and heat transfer characteristics of actual engine turbine disk cavity under experiment case with normal temperature conditions.

In the face of the complex three-dimensional (3D) flight environment under the constraints of terrain, no-fly zone, height limit, weather and other threats, the traditional reinforcement learning unmanned aerial vehicle (UAV) path planning algorithm has the problems of unreachable target points and dimension explosion. This paper proposes a path planning method for UAV in complex 3D environment. Based on the traditional reinforcement learning Q-Learning algorithm and the principle of artificial potential field (APF) algorithm, this method modifies the reward function generation mechanism in Q-Learning algorithm. The improved Q-Learning algorithm generates a dynamic reward function by judging the action of each step combined with environmental information. The reward function combines the good performance of the artificial potential field algorithm to make the reward accumulation process smoother. Finally, the typical complex mountain area scene is selected for simulation experiments. The experimental results show that the path planning algorithm designed in this paper can carry out feasible path planning for UAV in complex 3D environment.

Most of the existing propulsion systems that can rotate around the rotation axis and change the pitch angle of the propeller are applied to helicopters and ships. Their structure or weight cannot meet the requirements of lightweight and high bearing performance for near-space aircraft. To improve the adaptation range of near-space aircraft, this paper proposes a new variable-pitch vector mechanism for propellers based on a sine mechanism. The mechanism can adjust the blade angle of the propeller to produce unbalanced thrust. Firstly, the structural design and optimization of the variable-pitch mechanism are carried out, and the transmission system is designed according to its kinematics and statics. Secondly, the parts with high stress in the mechanism are analyzed using ANSYS. Finally, the principle prototype design and experiment are carried out. The experimental results show that the pitch-change mechanism designed in this paper can be matched with a pair of propellers of 6 m in diameter. When the propeller is running on the ground at 200 rpm, the pitch variation error is less than 0.5°, and the weight of the mechanism is only 18.78 kg.

This article conducted flow field refinement tests on a high load compressor using steady-state five hole probes, high-frequency dynamic probes, and blade probes, and obtained detailed inter stage flow field characteristics such as total pressure, total temperature, and Mach number. The results showed that by analyzing and comparing the flow field parameters of the compressor’s overall performance and inter stage performance tests with CFD design performance, the main characteristics that affect compressor performance can be effectively obtained, Obtain the flow field performance of the blade near the end wall and upstream and downstream blades, among which the steady-state five hole probe and dynamic single hole probe effectively overcome the problem of limited conventional measurement space for the compressor; The blade probe obtained detailed flow field distributions of performance parameters along the radial and circumferential directions of the 1–3 stage rotor, providing experimental data support for compressor flow field diagnosis and performance optimization.

As the brain and central nervous system of aircraft, Integrated Modular Avionics (IMA) system has a significant impact on the safe flight of aircraft. In addition, due to the internal cross-linking of multiple components in the IMA system, it is often difficult for troubleshooting when hardware components fail. Therefore, this paper proposes a distributed avionics communication and maintenance software with an actual hardware status monitoring. A lightweight distributed hardware platform based on microcontroller units (MCUs) has been designed to form a communication network to monitor the status of hardware components within the IMA system. The software design is as follows. Firstly, the MCU’s rich ADC, SPI, I2C and other peripheral interfaces are used to collect hardware information. Then, the collected hardware information of each module and sub-card inside the IMA platform is tested and the status of each test item is recorded as normal or faulty. Finally, the processed status information of each component is reported to the CPU on a single module and the core control node in the entire IMA platform for overall synthesis. The proposed software in this paper has been applied in practical engineering. It helps to improve the testability and maintainability of IMA system, and provides necessary auxiliary analysis for later troubleshooting.

The ACARS data is an important data source for Real-time flight status monitoring. However, ACARS data is affected by unstable factors during transmission and storage, resulting in complex missing situations. We focus on a data-driven class of methods based on deep learning applied to the reconstruction of ACARS data. The main work and innovation points are as follows:We categorized four missing patterns and generated corresponding datasets for training and testing models. The GAN architecture is adopted to deal with the problem that the ACARS data are dimensionally wide and difficult to be extracted. Encoder and decoder are used to form the generator of GAN, allowing the model to compress existing information into deep features and then generate a complete data set. And the attention mechanism is introduced to enhance the learning ability of the model for long-distance information. Finally, the effectiveness of the proposed method is verified by comparing it with different reconstruction models under four missing modes and ablation experiments.

In order to measure the traffic in the programmable network more accurately, the single-point traffic measurement method and network-level traffic measurement method are studied. In order to overcome the shortcomings of existing single-point traffic measurement algorithms, a single-point traffic measurement method, Flexible Sketch, based on counter and Sketch, is proposed, the simulation results show that the algorithm can effectively improve the accuracy of the measurement. The key measurement node assignment problem in network-level traffic measurement methods is investigated, and an approximate algorithm based on Lagrangian relaxation is proposed, which can effectively solve for a better measurement node assignment scheme. Considering the positive correlation between the computational complexity and the size of the network, a new genetic algorithm is proposed. The simulation results show that the two algorithms can solve the optimal measurement node allocation scheme, achieve network-level traffic measurement, and obtain higher measurement accuracy.

Cellular structure is an ideal way to realize adaptive flexible deformation of wings due to its lightweight, high stiffness, high building speed and reusable characteristics. On the one hand, the cellular structure can maintain the stiffness of the adaptive wing under aerodynamic loads, on the other hand, it can also be used as a driving structure to make the overall structure produce the expected deformation. In this paper, we designed a cellular variable camber wing, including cellular structure and drive system, and carried out modal analysis and static analysis of cells. The cellular structure is processed by 3D printing, and the wing assembly and drive system installation are finally completed. The deformation test of the variable camber wing is carried out by motor control. The results show that the deformation of the variable camber wing of the cellular structure is more flexible and can meet the requirements of the target deformation angle.

The flight control and landing gear systems of civil aircraft are generally driven by hydraulic system, which is the key system of aircraft. In the early days, common mode failures and events were not fully considered in the hydraulic system tube layout of passenger aircraft. However, with the occurrence of many air disasters caused by the unreasonable hydraulic system tube layout, people have a deeper understanding of the challenges of aircraft safety brought by the unreasonable hydraulic tube layout. The main landing gear bay is the intersection area of tire burst and rotor burst. How to rationally arrange the hydraulic system tube of passenger aircraft in this area has become an important subject to be solved. This paper takes a civil aircraft as an example to introduce a hydraulic tube layout method for main landing gear bay. This method focuses on the analysis of the influence of special risks such as tire burst and rotor burst on the safety of hydraulic system tube, and also makes a simulation of how the hydraulic tube meets the maintainability requirements. It provides a set of effective layout and analysis guidance method for the hydraulic tube of main landing gear bay.

During the launching phase of a small folding-wing UAV(SFUAV), the wings undergo drastic changes in aerodynamic and mass characteristics, the rudder efficiency is low and the anti-disturbance ability is poor, making it highly susceptible to environmental wind disturbances. This study focuses on the motion characteristics of SFUAV in the launching process and the launching safety in wind disturbance environments. Firstly, the wings unfolding dynamic model is established. Secondly, the impact of different wing-unfolding time on launching safety is investigated in calm environment. Furthermore, the effect of different wind speeds and directions on launch safety is analyzed. Finally, to enhance the launching safety of SFUAV against crosswind disturbances, a PID controller is designed to increase the flight stability and safety of the launching process.

It is well known that waverider vehicles have several potential uses in the aerospace industry. In this study, a low-complexity neural back-stepping control approach for waverider vehicles that is susceptible to input saturations is described. To begin with, a reliable back-stepping controller with a simple radial basis neural network is created for the usual waverider vehicle model. Then, a better prescribed performance control strategy for waverider vehicles is used to deal with the fragile problem of prescribed performance control (PPC) methods due to actuator saturations, which can ensure tracking errors satisfy the anticipated transient performance with input saturations. Finally, MATLAB simulations with perturbed aerodynamic parameters are used to demonstrate the efficiency of the suggested control schemes.

In injection molding transparency, cavity pressure determines the evolution of the polymer inside the mold cavity. The profile of cavity pressure and its repeatability have very strong influence on the quality of the molded transparency, particularly, the dimensional accuracy. To understand the cavity pressure behavior of the melt in injection compression molding, three pressure sensors are equipped in an injection compression mold and polycarbonate plates were molded by injection compression molding at different process variables. In addition, the thickness of PC plates and the cavity pressure of melt were compared. The results show that the variables of compression stage make the plates thickness and cavity pressure exhibit different behavior with respect to injection velocity. High injection velocity and high melt temperature is beneficial to both of the uniformity of thickness and cavity pressure.

Aerocraft operational integrity (AOI) is a fundamental requirement for aerocraft operational suitability (AOS) and aerocraft operational effectiveness (AOE), and it provides a more comprehensive overview of the general quality characteristics of an aerocraft. Prognosis and Health Monitoring (PHM) technologies are widely used in aerocraft systems. This paper briefly introduces the basic concept and expression methods of aerocraft operational integrity and some of the basic PHM technologies. The paper then analyzes in detail the mechanisms by which PHM technologies improve aerocraft operational integrity, including how they improve the degree of aerocraft operational integrity, inherent readiness rate, and inherent health degree. Finally, the paper presents the improvement processes of aerocraft operational integrity based on PHM technologies, which follow aerocraft health state analyses, residual service life prediction, and maintenance decisions.

The advanced aviation equipment is developing in a complicated and refined direction. There are many kinds of complex and numerous connecting structures between various parts and mechanisms, and the simulation of connecting structures has become an important part of structural analysis software. When dealing with joint element, the existing aviation autonomous structural analysis software SABRE generally adopts the method of linear elimination to eliminate the constraint relation from the total stiffness matrix of the structure. This method is efficient in solving simple models, but when dealing with complex aviation structures containing a large number of connecting structures, it will destroy the sparsity of the total stiffness matrix of the structure, which has a great impact on the efficiency of SABRE. This paper has in-depth research on solution technology of large-scale joint elements based on augmented Lagrange theory, innovatively transformed the constraint relationship into the element stiffness matrix expression form of joint element, and realized the development of a new joint element solving module in SABRE. Finally, the engineering application example test shows that the new method can effectively improve the solving efficiency of the autonomous structural analysis software SABRE without changing the solving accuracy.

Water entry is of great significance for the design of air-water trans-media vehicles and related weapons. The effect of surface characteristics on the hydrodynamics during water entry is a new research hot spot. However, there are few studies on the effect of surface roughness. Based on the experimental result and force analysis of the contact line model, the friction model is proposed to describe the contact for the rough surface. The simulation results show that the proposed friction model can accurately reflect the separation position with different rough surfaces during water entry. The water entry of a cylindrical structure with asymmetric surface roughness is studied by the established numerical method. The result shows that controlling the water entry trajectory through surface roughness is feasible.

Bonding technology, as one of the three aircraft manufacturing connection technologies, has been widely used in advanced aircraft. Foreign aircraft structure bonding technology has been quite mature, but Chinese helicopter bonding technology is in the process of continuous practice and improvement. EC175 helicopter represents the level of advanced aircraft in the world in the 21st century. It is the first equal risk cooperation project developed by China and western country. There are 31 kinds of honeycomb sandwich products with trapezoidal cross-section in EC175 helicopter. Affected by the trapezoidal closed sandwich structure, the failure rate of frame-honeycomb de-bonding is more and 63% in actual production, which seriously affected the production cost and restricted the progress. This paper analyzed the reasons from three aspects: structure, material and process. Through the optimization of bonding assembly process combined with product structure optimization, this kind of failure rate is effectively reduced and the technical level of helicopter structure bonding manufacturing is improved.

Based on a axial flow single-stage high reaction supersonic high-pressure turbine (HPT), HPT designs with different reaction levels were constructed, and research was conducted on installation angle caused by turbine guide groups in aviation engine engineering applications. The numerical simulation method was mainly used to analyze influence of installation angle of supersonic HPT guide vanes with different reaction on performance parameters such as throat area, reaction, Mach number, and efficiency. The results indicate that if a large group design is selected for guide vane, that is, when flow capacity of HPT increases by 6%, the installation angle of guide vane required for high reaction supersonic turbine changes relatively large, and the variation pattern of guide vane throat area is consistent with the variation relationship of installation angle. As the installation angle increases, turbine reaction gradually increases, and the change of reaction is approximately linear with installation angle. However, the shock wave enhancement in the channel of supersonic turbine blade with high reaction is particularly significant, leading to reduce turbine efficiency, and efficiency of supersonic turbine with low reaction gradually improves with increasing of installation angle.

In this paper, a control scheme is developed for attitude system of a fixed-wing unmanned aerial vehicle (UAV) subject to unknown external disturbance. First, the dynamic equations of attitude system are introduced and the control-oriented model (COM) is established. Then, an adaptive-gain sliding mode (AGSM) algorithm is proposed to handle the effects of unknown external disturbance such that the expected equivalent sliding-mode dynamics can be obtained. Based on the above design, an actor-critic structure-based ADP approach is employed to generate the nearly optimal control law. Finally, the validity of our proposed control scheme is demonstrated via simulation.

Aircraft hatch is a very important component, which provides the most basic function and security for the use of aircraft. In the process of landing gear’s loading and unloading, the non-command unlocking of the cabin door occurred. This failure was analyzed and checked according to the principle of the lock structure of the door actuating cylinder. Using AMESim modeling and simulation analysis, it was found that the failure was caused by the abnormal pressure of the main return oil line and the low pressure of the lock opening in the actuator cylinder. By increasing the stiffness and the pre-compression of the spring in the lock, the unlocking pressure and the reset ability of the spring seat are increased. The working performance of the door actuator is improved, which is verified experimentally.

Through the analysis of the aerodynamic characteristics of model aircraft with a scale of 12.5%, 50% and full-size, respectively, the feasibility of using a scaled model to simulate a full-size aircraft is proved. At the same time, the six-degree-of-freedom nonlinear model of three scaled models was established, and the influence of scale on aircraft trim and natural characteristics was studied based on the Froude number similarity criterion. Additionally, based on the autonomous flight control law designed by the 12.5% scaled model, the autonomous control law parameters of 50% scaled model and full-size aircraft were obtained by using the similarity criterion. Through digital simulation, the nonlinear model of the full-scale wing-body fusion aircraft is simulated and verified, and the influence of the scale on the flight control system can be obtained. According to the above tests, it can provide a certain reference for the scaled flight test of the newly layout aircraft.

The refueling/receiving system composes of the refueling tanker aircraft and the receiver aircraft is of great significance to the formation and promotion of the national air force. Due to the influence of the space flow field and the change of the motion characteristics of the refueling tanker aircraft, the pilot of the refueling tanker aircraft needs to understand the flow field characteristics deeply and drive carefully in order to complete the risky subject. Taking a typical refueling tanker aircraft as an example, this paper studies the characteristics of the wake flow field of the refueling tanker aircraft. Taking a typical refueling tanker aircraft as an example, the simulation model of the refueling tanker aircraft is established, the dynamic characteristics of the refueling tanker aircraft are studied, and the control suggestions in the process of oil loading are given. The results show that this research has important receiver aircraft significance and guiding value for the development of refueling/receiving formation and docking.

The industrial revolution has promoted the rapid development of human society. The human industrial revolution has now developed into the industrial 4.0 era of intelligent production. The proposal of the “Made in China 2025 strategy” puts the traditional aviation manufacturing industry at a critical stage of transformation to intelligence. In the process of transformation to intelligence, how to establish and implement the enterprise’s intelligent factory strategy and promote the deep integration of the new generation of information technology and manufacturing will become an important layout direction of the Made In China 2025. Based on the above background, this paper first introduced the background and significance of intelligent factory construction, and then analyzed the development status of traditional aviation manufacturing industry; Secondly, it expounded the overall framework and implementation plan of intelligent factory construction; Finally, taking a large regional airliner assembly workshop as an example, the existing problems are analyzed, and the implementation results of intelligent factory construction are introduced, which provided a reference for the construction of intelligent factory in aviation manufacturing industry.

Aiming at the situation that the typical stiffened panel structure in aeronautical engineering will be impacted by shelling vibration, resulting in the failure of the structure and equipment vibration, the fractional order PID (FOPID) controller is used to control the transient impact response, which accelerates the attenuation of the structural response speed. Taking the stiffened panel with the macro fiber piezoelectric composite (MFC) piezoelectric sheet as the controlled object, the particle swarm algorithm is used to optimize the controller parameters, and the RMS reduction ratio of the random response of the system model and the reduction of the PSD spectrum peak is reduced. As the objective function of the controller, a corresponding fractional-order PID controller is designed. The crank-link mechanism is used for transient excitation, and the results show that fractional-order PID can effectively improve the decay rate of the transient excitation response of the stiffened wall plate structure, and the logarithmic decay rate of the transient excitation response of the structure is increased by at least 142%. The controller has good application potential for active control of the transient excitation response of stiffened panel structures.

This paper aims to solve the problem of lack of high-quality fault data for fault diagnosis of complex hydraulic systems and typical component failure models. Based on root cause analysis, the paper combines the failure mechanism and key parameters of engine drive pumps, electro-hydraulic changeover valves and hydraulic cylinders, which are common components in hydraulic systems. The paper builds simulation models of these components under different test bench conditions, which can generate operational health and failure data under different operating conditions. The paper analyses the flow and pressure data from multiple collection points in the system and components with multiple failure modes and demonstrates that the proposed method can support the fault diagnosis data requirements and provide data support for fault diagnosis and condition prediction of the system and components.

The fuel system is a large and complex pipeline system on the aircraft, which include a series of functional accessories such as pumps, valves and bends [1]. The current distribution of aircraft fuel tank is the ventilation tank-large wing outer tank-large wing inner tank-central tank. The fuel is stored in the tank as the blood of the aircraft. If the aircraft tank is damaged, which leads to aviation fuel leakage, and aircraft quickly lost propulsion, and aircraft loses lift, cause aircraft crash and fire, explosion, and landing site uncertainty will cause huge safety hidden danger to people’s lives and property. Therefore, it is great significance for the safety and reliability of aircraft to reduce the pressure difference between inside and outside of aircraft.

Aimed at the bottleneck problem that the accumulated transmission results of assembly errors cannot be predicted in advance, and a method was proposed for coordination error transmission accumulated calculation and coordinate dimension chain construction. Through analysis of assembly error coupling relationship and nonlinear transmission path model, construction method of assembly feature geometric error model based on key measurement points, multidirectional hybrid expression method for coordinated dimensional chain of multi separation surface wing assembly, modeling technology for error transmission and accumulation in multi process assembly of complex products, accurate construction of assembly coordination dimension chain and quantitative analysis of accumulated assembly error transmission results could be achieved, which could provide data foundation for construction of assembly error spatial dimension chain and optimization design of assembly process for segmented wing structure.

This paper proposes a contamination model based on the block diagram of the transfer function to study the pollutant migration process in complex multi-loop systems. The existing pollution research results of single-loop systems are difficult to be directly applied to multi-loop systems due to their different structures and characteristics. The pollution model can quantitatively analyze the pollution degree of each section of the multi-loop system and evaluate the health status of the circuit. The paper also obtains the following conclusions through simulation analysis: (1) The system pollution degree will reach dynamic equilibrium under the joint action of the pollution invasion element and the filter, but the pollution degree of each section of the circuit is different. The simulation results can evaluate the health status of each circuit and provide a reference for the installation of the filter and pollution-sensitive element. (2) There is a non-linear relationship between the repeat filtration and the filtration performance of the filter. As the repetition filtration degree increases, the filtration performance in the process has a rapid decrease. Repeat filtration degree parameters can determine the timing of filter replacement. (3) The minimum filtration degree parameter for this hydraulic system metering unit to achieve the desired cleanliness less than 9 under constant contamination intrusion condition is 6.14, and the limit scale capacity of the filter is 221 g. This paper provides a new method and reference for contamination research of complex multi-loop systems.

In the damage detection of a joint structure based on guided waves, the diagnosis of invisible damage is a challenge. The complex multi-nail structure and the influence of complex load environment are the main factors that affect the reliability damage monitoring of the joint structure. Therefore, it is essential to effectively improve the reliability of damage monitoring of joints under load conditions. In this paper, an online damage monitoring method based on the Gaussian mixture model is proposed. In the monitoring process, the Gaussian mixture model modeling method was used to model the characteristics of guided wave signals at different times under the influence of load factors. Then, the probability difference damage index Diff was used to represent the change in the probability distribution between the models to achieve reliable damage monitoring. Fatigue test results of joint structures show that this method can realize reliable damage detection of joint structures under load environments.

The heat transfer and flow performance of lubricating oil in an air/lubricating oil heat exchanger were simulated by the realizable $$k - \varepsilon$$ k - ε model with enhanced wall treatment in ANSYS FLUENT, so as to obtain the variation rule of the heat transfer factor j and the friction factor f with Re. Simlarly, several literature empirical correlations and experiments were adopted. By comparison and analysis of ANSYS FLUENT numerical simulation results, literature empirical correlations and experimental results, it was found that the heat transfer factor j of lubricating oil in channels with serrated fins could be predicted better by the realizable $$k{ - }\varepsilon$$ k - ε model with enhanced wall treatment (the relative deviation of 7% ~10%) and Wieting correlations (the relative deviation of 4% ~9%). Moreover, the friction factor f of lubricating oil could be predicted better by the realizable $$k{ - }\varepsilon$$ k - ε model with enhanced wall treatment (the relative deviation of −11% ~−5%), Wieting correlations (the relative deviation of −8% ~−2%) and Joshi&Webb correlations (the relative deviation of −8%  ~−1%).

Body freedom flutter of carried flyers need to be investigated when such flyers are hung on the elastic structures of twin-fuselage aircraft (TFA). Due to the unique structural layout, the structural dynamics of TFA might be coupled with the aerodynamic loads on the flyer which leads to a special flutter behavior. In this behavior, the structural flexibility of the flyer could be neglected, while the flyer’s motion attributes to the TFA’s dynamics. In this work, the body freedom flutter of carried flyer is studied using p-k method in frequency domain. The structural model is established utilizing finite element beams. The aerodynamic loads are evaluated by doublet-lattice method. The coupling of structure and aerodynamics is established through displacement integration. The dynamic characteristics of TFA is compared with traditional single-fuselage aircraft with the same wing aspect ratio. The mode coalescence between the plunge and pitching of the flyer is found in the TFA aeroelastic system. These modes of flyer motion attribute to the vibration of the middle wing in TFA.

The minimum Hamming distance of satellite-based Automatic Dependent Surveillance-Broadcast (ADS-B) signals at low signal-to-noise ratios (SNRs) is only 6, which is inadequate to meet airspace surveillance requirements in terms of packet decoding probability (PD). An enhanced error correction algorithm combined with directed density-based clustering for satellite-based ADS-B signals is proposed to address this phenomenon, and its performance is verified by simulation. Firstly, the density-based clustering model will cluster a given signal sequence according to its partial minimum Hamming distance from other sequences, reducing the chance of undetectable errors. Secondly, the proposed error syndrome matrix built offline streamlines the Brute Force correction, preserving on-star resources. Finally, the {a, b} algorithm compensates for low SNR-induced unreliability of confidence arrays through error correction depth a and error correction capability b. The simulation results show that the {20, 10} error correction algorithm can achieve a PD of 86.4% at the minimum SNR of satellite-based ADS-B signals.

In this paper, a composite system of Unmanned Aerial Vehicles (UAVs) including path planning and dynamic obstacle avoidance is proposed. The system can deal with complex low-altitude environments, achieve autonomous flight path planning, and dynamically avoid obstacles. When obstacles were detected at a relatively far distance, a local collision-free flight path near the affected route is planned online using a plant growth algorithm proposed without changing the current flight state of the UAV. When a moving obstacle suddenly enters the UAV’s flight path at a closer distance, a situation-aware dynamic obstacle avoidance algorithm based on artificial potential fields is preferentially activated to respond at the fastest speed. Meanwhile, the local planner is also used to plan a new local collision-free path again, ensuring the UAV’s flight safety to the greatest extent with minimal cost. The effectiveness of the intelligent UAV composite path planning and dynamic obstacle avoidance system is demonstrated in simulation environment and real-world experiments.

A fault diagnosis method for rotor system of small and medium aero-engine is presented. In this method, a strain gauge is attached to the elastic support of the rotor system to obtain the dynamic stress signal of the elastic support in the working process. Combined with the respective advantages of EMD and PAC, the dynamic stress of the elastic support is firstly decomposed by EMD, and PCA is used to obtain the IMF principal component, and then the noise evaluation criteria is established by the correlation coefficient to eliminate the interfering principal component. Finally, the remaining principal component is reconstructed and the noise reduction signal is obtained. Practical application shows that this method can diagnose rotor system faults effectively.

This article mainly studies the robot automatic resin sand spraying process, especially its impact on the surface roughness and adhesion of composite materials. The surface roughening of aviation composite materials mainly includes roughening before bonding, roughening before aluminum spraying, and roughening before painting. Traditional roughening process schemes mostly include manual polishing, manual sandblasting, etc. This article is based on an eight axis linkage robot automatic resin sand spraying system. The main research focuses on the influence of different process parameter combinations such as sandblasting pressure, movement rate, and spraying frequency on the surface removal degree of aviation composite materials before spraying. The coarsening degree is characterized by metallographic microscopy, surface roughness, and tensile strength, providing theoretical support for the selection of robot automatic resin sand coarsening process parameters.

Manned helicopters and UAVs operating together is a new combat style for Army Air Corps helicopter equipment. LVC simulation is an effective test and verification method, whether it is to conduct operational test analysis or to realize training evaluation. Based on the characteristics of manned helicopters and UAVs, we summarize the requirements and difficulties, and summarize the related key technologies, propose a simulation framework, and realize the verification of manned helicopters and UAVs cooperative combat system under LVC simulation through the simulation design process.

Aiming at the flight test for stall protection control law of civil aircraft, its main functions were summarized based on the analysis of the typical structure of control law. And the purposes were provided for the flight test of the stall protection control law. The flight test was divided into two stages. The details of the contents, operations and evaluations for flight test were studied. The test risks were analyzed and could be reduced by the measures provided. And the key strategies for adjusting parameters of the stall protection control law were provided and the engineering recommendations were made too. The technologies for the stall protection control law were verified effectively by the methods of simulation and flight test. This study provides useful reference for the design, development, and flight test of the stall protection control law for civil aircraft in China.

The finite element dynamics simulation and modal test for monorail rocket sled. Firstly, the finite element model of the monorail rocket sled is established and the modal simulation analysis is carried out, and its natural frequency and modal mode shape within 400 Hz are obtained. Secondly, a monorail rocket sled modal test model is established, and the modal test analysis of the free-state monorail rocket sled structure is carried out by hammering method, and the natural frequency within 400 Hz of the monorail rocket sled structure and its corresponding modal mode shape are obtained. Finally, the test results and finite element simulation results are compared and analyzed in detail. The results show that the natural frequency error of the two is less than 15%, and the experimental mode shape is consistent with the finite element simulation mode shape, which proves that the simulation analysis results are true and reliable.

Based on the S-N curve of the water brake device material, the nominal stress method was used to calculate the fatigue life by comparing the stress concentration coefficient and nominal stress of the structural fatigue danger part, combined with the fatigue damage accumulation theory. Through empirical formula combined with experimental correction, according to the t-distribution theory, the S-N curve of the water brake device material is obtained according to the confidence and error requirements. Combined with finite element simulation analysis, the load spectrum and danger point stress are extracted, and the fatigue simulation and analysis software is used to identify the danger point of the water brake device and calculate the fatigue life.

With the development of more electric/all electric aircraft, the use of electricity in airborne equipment has increased, leading to a trend towards more comprehensive integration. High-voltage DC power generation system has the characteristics of high capacity and high efficiency, which offers obvious advantages in aviation DC power generation system. Multiphase/Multi-unit motor have clear advantages in the field of large capacity power generation. By using existing power tubes of a certain level, which can achieve large capacity power transformation. Compared to three phase motor, they offer advantages such as larger capacity, higher reliability, and greater control flexibility. As the primary components of aviation power systems, aviation generator and rectifier combine to form an aviation high-voltage generation system. Due to the high speed of the aviation generator and varying DC bus loads, the output voltage of the aviation rectifier is not fixed, requiring a rectifier control strategy that adjusts the contribution according to real-time feedback voltage and current to maintain either constant load-side power or a constant voltage. This thesis explores the control strategy of a multiphase/multi-unit permanent magnet synchronous generator rectifier system, and completes the algorithm validation of the rectifier system of the high-voltage generator.

In order to supply multifunctional requirements, aerodynamic numerical simulation is carried out for the new concept configuration of loitering munition. Firstly, the basic design features of the concept configuration are reviewed. Secondly, the numerical simulation method was validated and applied to the aerodynamic analysis of loitering munition. And then, the longitudinal and lateral aerodynamic performance of cruise and flights at variable speeds are simulated by numerical simulation method. Finally, the numerical simulation of rapid maneuvering flight was conducted and analyzed. The research shows that the loitering munition has good longitudinal and lateral static stability at multi-mode flight, which can achieve self-balancing. The cruise factor of the long endurance cruise mode and the maximum lift-drag ratio is greater than 20 respectively.

Considering the problems of dynamics coupling between six degrees of freedom, internal modeling error and external wake interference in the process of carrier landing, this paper uses RBF neural network with a novel NN parameter learning method called minimum parameter method to estimate and compensate the composite interference, so as to realize the decoupling control and robust control. Firstly, according to the principle of time scale separation, the multi-layer dynamic inverse control of 6DoF dynamics is conducted. Then, the RBF neural network is designed for dynamic compensation to solve the problem of compound interference. To meet the requirements of real-time control, the minimum parameter learning method is applied to transform the RBF multi-parameters estimation into a single parameter estimation which is proved feasible with the Lyapunov method. The simulation results show that the system has good robust performance to ensure the accuracy and safety of carrier landing.

Based on the latest developments in gust alleviation technology, this paper studies and establishes the modeling methods, control scheme design and practical alleviation methods for gust alleviation techniques. The effectiveness of the modeling method and the gust alleviation control scheme was verified by wind tunnel tests.

With the development of electronic technology, more and more high-performance and high-power equipment are installed on the aircraft, which additional ventilation cooling system to ensure the normal operation of the equipment. The typical cooling methods of ARINC standard equipment are summarized in this paper, and the flow design conditions of equipment ventilation cooling system are proposed according to ARINC standards and specifications. Under the assumption of isentropic flow and ideal gas conditions, the mathematical models of cooling flow of equipment cooling system are established and the design method of equipment cooling system are put forward. For a newly installed electronic equipment, the electronic equipment cooling system is designed, and the cooling capacity of the equipment cooling system is analyzed by CFD, which provides a reference for the equipment cooling scheme of subsequent installed equipment.

The traditional task based training mode can no longer meet the safety requirements of the current large amount of flight training. On the basis of the new era training idea of "implementing flight training based on core competency", the construction and application scheme of pilot core competency virtual simulation experiment platform is proposed. The program mainly aims at cultivating pilots' nine core competencies to build a flight virtual simulation experiment platform, and divides the platform application into three practice modules: basic, comprehensive and expanded. The practice shows that the construction and application of this platform has transformed the traditional mission based flight training, solved the problems of "focusing on aircraft control and ignoring core competence" in the flight training process, and can effectively improve the quality of flight theory learning and training, which is of great significance to training high-quality flight technicians.

Aiming at block failure of a type of solenoid valve, the clearance at the control plunger section was trade-off, and the purpose is to solve the block while not causing over leakage of the whole valve. According to the analysis of the internal leakage channel of the solenoid valve, it is known that there is no leakage in the clearance at the control plunger section under the power-off condition, and the leakage through the clearance is far less than the allowable value when the power is turned on, that is, the clearance can be increased to eliminate the jam. Within the allowable range of leakage, calculated according to the annular gap flow formula, when the eccentricity of the control plunger in the sleeve takes the extreme values 0 and 1, the unilateral maximum allowable values of the clearance are 6.3 μm and 4.6 μm respectively. According to the estimation of the leakage test results, the eccentricity of the control plunger in the sleeve is 0.42, and the unilateral maximum allowable value of the clearance is 5.8 μm. By increasing the clearance of the control plunger section, the block failure of the solenoid valve is eliminated, and no over-leakage occurs.

This paper mainly studies the robot automatic flame spraying aluminum technology in composite material. Through experiments, the mathematical relationship between spraying angle, track spacing, wire feeding rate, measurement time and measurement resistance is studied. It provides theoretical support for the selection of process parameters of robot flame spraying aluminum, and provides thinking and reference for the automation research of other spraying majors.

Accurate measurement of dynamic exhaust gas temperature (EGT) in Aeroengine is a challenging task. The most common, and also the most practical, method of measurement is to insert a physical probe, for example, a thermocouple sensor, directly into the exhaust flow. The structure principle of the sensor determines there are temperature measurement lags when the EGT changes dynamically. A theoretical model of the heat transfer phenomena that take place in the exhaust flow has been developed to decrease the dynamic error of measuring the exhaust gas temperatures with the thermocouple sensor. And a wind tunnel experiment had been done to obtain the actual time constant of the EGT sensor in variety of dynamic conditions. The theoretical time constant model was compared with the actual time constant to prove its effectiveness. In this work, the authors introduce a new temperature compensation algorithm that can modify the dynamic response errors introduced during the measurement. The algorithm was designed and verified on a real Aeroengine bench test. The fact that the dynamic modified values of EGT obtained in the real engine test are basically consistent with the theoretical values, proves the accuracy of the dynamic modification algorithm of the EGT.

Most modern turbojet aircraft are designed with thrust reverser to improve the economy, availability and safety of the aircraft. However, if the thrust reverser is turned on at an inappropriate time, it will not only decrease the effect of the thrust reverser but also may trigger safety accidents. Therefore, the design of thrust reverser and the verification of airworthiness compliance have become the key issues of the airworthiness Bureau. However, the thrust reverser lacks the technical reserves and the development experience at home, and it will be difficult to solve the problems in technology and verification if it is completely based on the domestic independent research. Hence, the working logic of the thrust reverser of foreign aircraft types is studied, and the response of the thrust reverser in the process of wheel-load hopping is mainly focused on. Firstly, QAR (quick access recorder) data of 250,000 flights were collected and decoded for four aircraft types, including B737, B787, A320NEO and A350. Secondly, the decision condition and the samples of wheel-load hopping are defined. Then, typical scenarios are screened to analyze the response of the thrust reverser in the process of wheel-load hopping. Finally, the frequency and duration of the hopping of different types of aircraft and the response of the thrust reverser are quantified, and the statistical conclusions are drawn. This paper can provide data and theoretical support for the development and airworthiness certification of thrust reverser of civil transport aircraft.

Because of the advantage properties,the spread tow structure was widely used in composite material industry. TexGen software was an open source software which developed by University of Nottingham to model the geometry of textile composites. In this study, the Python script was used to create the textile of experimental part and the spread tow structure was created though adding nodes to the existing model in TexGen, which was the first time that the TexGen was used to create spread tow of composite material. After that the domain of the model was generated, as well as finite element mesh was created and two types of structure data were generated from the mesh. More importantly, the model created in the study could not only meet the requirements of the experimental part but also be spread to other structure.

An approach to simulate the total pressure of the pitot during ejection is proposed by combining the numerical simulation of seat motion trajectory and dynamic CFD technology in this paper. By establishing the simulation model of cabin, human-seat system and pitot, the seat motion parameters obtained from the simulation of the motion trajectory are used as input to write the UDF, the motion boundary of the human-seat system is specified, and the grid update during the movement of the seat is realized by dynamic grid method, and the influence of the wake field of the cabin on the total pressure of the pitot under different ejection states is analyzed. The simulation results show that due to the influence of the wake field of the cabin, the perceived total pressure of the pitot first increases and then decreases, peaks at about 0.08s after ejection starts, and is greater than the test total pressure in the subsequent 0.01s time range, and the maximum deviation reaches 14.65%. This peak can be reduced by filtering, reducing the deviation to less than 5%. The simulation model and algorithm are calibrated, and the deviation is less than 2%, which meets the engineering requirements, and the simulation results can provide a basis for the optimization of seat aerodynamic layout and program controller data processing strategy.

This paper investigates the robust attitude control for wingtip-connected multibody aircraft, using preview-based control compensation mechanism to address the issues of inherent wingtip couplings. A constrained multibody dynamics model is first derived to obtain the nonlinear and linearised formulations for multibody aircraft. The H $$_{\infty }$$ ∞ control is employed to synthesize the pitch angle and forward velocity controller in the longitudinal channel, while the H $$_{\infty }$$ ∞ preview control is employed to synthesize the roll angle and yaw rate controller in the lateral channel. The preview control scheme enables the usage of future reference commands as feedforward information to synthesize appropriate control compensation to reduce the impact of wingtip couplings between adjacent aircraft units. Simulation studies conducted based on the nonlinear model show that the preview-based H $$_{\infty }$$ ∞ control system is able to achieve better control effectiveness and disturbance rejection performance, compared to the baseline regular H $$_{\infty }$$ ∞ control system without preview. These demonstrate that the mechanism of control compensation can greatly benefit the flight control of multibody aircraft.

Aiming to a new designed porous structure intake distortion generator, applying ANSYS WORKBENCH to process air-solid coupling simulation test to validate its strength. The main function of the facility is to form a target distortion flow field at inlet of a fan component test article to satisfy the testing requirement. Consider that this facility is characteristic for its porous, anomalous structure, which may introduce series zones of stress convergence, to avoid instinct plastic deformation or even structure breakdown occurring on the facility in the process of test, before its going into operation, strength validation on the facility under various working conditions is required to ensure its validity and security. Furthermore, in the condition that the strength of the facility does not ample to satisfy the requirement, based on the simulation results structure modification and reinforce schemes are given, further air-solid coupling simulation on modified structure of intake distortion generator strength are performed to evaluate the facility reliability.

The inhomogeneity of the metal continuous grain flow in preformed blank with complex structured cantilever ring is determined by billet geometrical parameters. In this paper, the influence of the geometric parameters of the blank on the flow of preformed metal is studied mainly by FEA, and then the geometric parameters of the cantilever ring preformed blank are optimized and designed based on the orthogonal method, and the order of influence is obtained, namely, the radius R of the round corner at the root of the cantilever ring branch > the angle α of inclination at the bottom of the branch > the fillet radius r of the branch end. A Second-order response surface model between displacement and geometric parameters of the blank is built by the response surface method, and the optimal geometric parameters are obtained: R = 11.89 mm, α = 12.87°, r = 3.92 mm. Combined with the experimental results, it is shown that each branch of the optimized preform can fill the branch cavity at the same time, and the maximum load of the preform is reduced by 16.6% compared with that before optimization, and the reliability of the optimized result is verified.

Icing has a negative impact on flight safety. As an important means of studying icing problems and validating high-precision numerical simulation software for icing, icing wind tunnel tests require higher reliability and more accurate uncertainty quantification. This paper describes the experimental setup of the AVICARI FL-61 icing wind tunnel, the spray system, and its performance. The repeatability of the icing wind tunnel spray system was confirmed through tests. Experimental research was conducted on the effects of air speed, water pressure, and air pressure on LWC, with results showing that LWC exhibits an approximately linear relationship with the logarithm of air speed, is proportional to the number of nozzles, and demonstrates an approximately linear relationship with the logarithm of water pressure. In the fitted formula for LWC and water pressure, air pressure exhibits an approximate linear relationship with the intercept term in the formula. The experiments found that parameter fluctuations are significant during the initial stage of the spraying process, which is unfavorable for studies sensitive to the initial icing.

With the increase of the number of UAVs and the complexity of the airspace, the risk of UAVs colliding with other objects is increasing day by day.The perception and avoidance for UAV is a technology research, which complements the development of technology research and policy management. In this paper, the rules of perception and avoidance are designed for UAV with different take-off weights, which provide the basis for the regulation of UAV. Firstly, according to the safe flight distance of different sizes of UAVs, the safety flight avoidance action is implemented. Secondly, the rules of perceived flight avoidance and the rules of flight avoidance are defined in accordance with the objective factors such as the maneuverability of different types of UAVs. Finally, based on the rules of flight avoidance, the evasive action of routine situation avoidance and maneuvering posture of UAVs is established. According to the characteristics of the model, this paper proposes the avoidance maneuvers including left-turn, right-turn, climbing, descending, accelerating and decelerating. Besides, the lateral and longitudinal avoidance maneuvers which based on L1 and fixed height are designed, and the corresponding avoidance priorities are also mentioned.

Slat cusp sawtooth and slat cusp extension are both potential small-size low noise devices on slat cusp, which have advantages of compatibility on certification rules and sturcture designs. By using the DES/FW-H hybrid simulation of the commercial code ANSYS FLUENT, the noise reduction performance of slat cusp sawtooth and slat cusp extension are investigated. Transient flow field results show that compared to slat cusp baseline, slat cusp sawtooth always brings higher or same level of pressure fluctuations, while slat cusp extension always keeps same or lower level of pressure fluctuations. Far field noise results show that compared to slat cusp baseline, slat cusp extension has a notable noise reduction performance, while slat cusp sawtooth has almost no noise reduction effect for directions to earth.

The pressure-bias-modulated (PBM) is an aircraft antiskid brake algorithm with great engineering application. Its control structure is simple, with few debugging parameters, and it is reliable to prevent the wheel from slipping. But the core parameter (reference deceleration rate) lacks adaptability to different runway. Aircraft tend to skid and anti-skid frequently under adverse conditions (wet and icy), resulting in inefficient braking. In this paper, the brake pressure is used to explore the runway conditions, and extended braking stiffness (XBS) is used to adjust the reference deceleration rate. The reference deceleration rate modified with runway exploration will replace the preset reference deceleration rate in the classic PBM algorithm. This gives the PBM algorithm the ability to identify runways. We established a single-wheel aircraft braking system model under simulation conditions, and verified the control algorithm under different runway conditions and time-varying braking torque disturbances. Compared with the classic PBM, the improved algorithm not only effectively reduces the number of wheel slips, but also improves the braking efficiency.

With development of information technology, the demands for equipment test have been persistently increasing. The evaluation of the system’s capabilities in simulated environments that closely actual environment has emerged as a critical area of focus in the assessment of equipment performance. As a result of the high level of correspondence between testing and training, the integration of training system resources can significantly improve testing and evaluation efficiency while also promoting resource reuse. In light of current experience in merging testing and training, this study endeavors to explore the integration of testing and training through the use of distributed simulation technology and LVC technology. The research emphasizes system architecture design and key technologies. Taking the civil airport ground anti-interference equipment as an example, an integrated test and training system was designed. The results show that the system realizes the interoperability between LVC training equipment and the collection of key test data. The experiment verifies the feasibility of conducting operation test using training equipment through the integrated test and training system.

Aiming at the problem of severe nonlinearity of supersonic civil aircraft maneuvering with high angle of attack (AOA), a flight control method based on the dynamic inversion (DI) is proposed in this paper. According to the time-scale separation principle, the supersonic civil aircraft control system is divided into attitude subsystem and altitude subsystem to design dynamic inversion controllers, respectively. Thereinto, the attitude subsystem is divided into internal and external loops according to different state quantities of response speed. The internal loop is used to track the pitch angle speed and the external loop is used to track the angle of attack instruction. The altitude subsystem is used for speed control. The simulation results of the proposed method show that the designed dynamic inversion vertical controller has a good tracking effect, and can quickly track the angle of attack command and the speed command. This method can effectively alleviate the nonlinear maneuverability and stability of supersonic civil aircraft flying at the high angle of attack.