Proceedings of the 6th China Aeronautical Science and Technology Conference

Achieving airport carbon emission peak is crucial for the civil aviation industry to reach carbon emission peak on schedule for airports are important infrastructure of air transportation. The LEAP-Airport model is developed based on the Low Emissions Analysis Platform (LEAP) model to forecast long-term carbon emissions of airport. Taking Nanjing Lukou International Airport as an example, 11 scenarios in 6 categories are set up according to abatement strategies, which are grouped into operational improvements, structural optimization, technological progress, and alternative fuels strategy. By simulating carbon emission trends from 2023 to 2035 under different scenarios based on the LEAP-Airport model, this paper analyses the effectiveness of various abatement strategies, providing a basis for formulating carbon abatement strategy for the airport. The results show that the Lukou airport will not be able to reach the carbon emission peak on schedule if no emission reduction measures were taken; the airport will still not be able to achieve the carbon peak target if the emission reduction efforts were made according to the existing policies; the airport is expected to achieve the carbon peak in 2030 with 574 thousand tons if the abatement measures were strengthened on the basis of the existing policies. Among the four types of airport emission reduction strategies, technological progress and alternative fuels strategies should be implemented as a priority, and the strength of existing policies should be increased to reduce emissions to achieve the peak target on time.

The general layout design of aircraft has been significantly developed in the aviation history of the past five score years. However, it is apparent to witness the bottleneck and hard to break through traditional creation in the last decade. In this paper, aiming at future’s war mode of systematic battle and considering the engineering application potential of cutting-edge technology, the general design of an original flying-wing and V-tail UCAV, which is mainly used for electromagnetic attack is described and modeled; Based on computational flight mechanics and principle of stealth, the performance parameters are provided and structure design is carried out; According to the division criteria of the fighter general arrangement, bay definition of the whole UCAV is launch. Besides, applying CFD means, the main aerodynamic characteristics especially the efficiency of two degree of freedom moving V-tail layout are analyzed. The results show the excellent cruise performance and acceptable maneuver characteristics of this platform which could be realized for a variety of task demands such as distributed detection, systematic countermeasures and focused killing. Moreover, this paper could be an effective reference for innovative aircraft design and exploration.

Aiming at the higher heat dissipation demand of future high-performance aero engine, this paper proposes a high temperature shape memory alloy thermal control valve, which expands the application scenario of thermal control valve without changing the shape memory material. Through the unsteady solid thermal analysis calculation, the temperature field distribution of the internal structure of the valve core at different times was obtained, and the excess temperature curve of the shape memory alloy spring in the insulated sandwich of the shape memory alloy valve was obtained. By analyzing the curve, the time constant of the selected shape memory alloy thermal regulating valve was calculated to be 81 s. The obtained time constant can be used to guide the material selection of heat insulation structure and memory alloy spring in the process of engineering development.

With the continuous development of aero engine technology, the heat dissipation requirements of lubricating oil system and high-power components of engine increase. It is necessary to cool a stream of high-temperature lubricating oil by using low-temperature external culvert air through air lubricating radiator. In order to verify the heat dissipation effect of the air lubricating radiator, it is necessary to carry out a series of component level heat transfer characteristic tests under typical working conditions, and modify the calculation model of the radiator based on the test results. In order to improve the calculation accuracy of the heat transfer model under all working conditions, the evaluation objective of the selection of the correction coefficient was proposed to be the average value of the absolute deviation between the test results of the heat transfer characteristics of the oil outlet temperature index of the air lubricating radiator and the calculated results of the model under typical state points. The evaluation objectives under a series of correction coefficients were calculated respectively, and the correction coefficients under the minimum condition of the evaluation objectives were finally selected. The screened correction coefficients were put into the original calculation model of air lubrication radiator heat transfer, so as to improve the calculation accuracy of the model under all working conditions.

Multi-UAV coordinated trajectory tracking is the most popular research problem at present. It is necessary to optimize and adjust the combined course of multiple UAVs and the motion trajectory of UAVs in real-time, and constantly pursue the dynamic optimal configuration between multiple UAVs and targets to improve and stabilize the positioning accuracy. Given the shortcomings of traditional centralized optimization methods, this paper proposes an advanced fuzzy graph convolution neural network model (FGTT). Because of the multi unmanned multi-source target and the irregular geometric structure, the graph convolution neural network can better optimize and process the trajectory tracking optimization method in non-European space. Several groups of verification show that this method can achieve higher tracking accuracy faster than traditional methods, The stability and accuracy of location and tracking are improved.

During ejection rescue, the parachute gun attached to a rocket-assisted ejection seat generates jet noise that may damage a pilot’s sensitive auditory organs; hence the effectiveness of hearing protectors, primarily a helmet and earmuffs, is evaluated. A parachute gun firing experiment is designed, and overpressure data with and without protection are measured simultaneously during firing using piezoelectric pressure sensors inside and outside dummy ears. A comparative study of the measured data is conducted using time domain analysis and wavelet transformation methods, and the results show that the jet noise generated by a parachute gun firing is a broadband signal, consisting of shock waves and impulse noise; different from the attenuation characteristics in the continuous noise environment, in the jet noise environment, the effect of hearing protectors is significant for extenuating the high-frequency components that are prone to injury, but not significant for extenuating the low-frequency components.

Al coating was fabricated by chemical vapor deposition on the nickel-based single crystal superalloy. The high-temperature oxidation behavior at 900 ℃ and 1000 ℃ for 200 h were detected by scanning electron microscopy, energy disperse spectroscopy and X-ray diffraction. Results indicated that the oxidation kinetics of the alloy substrate and Al coating were all in accord with the parabolic rule. Compared with the alloy substrate, the Al coating manifested lowest oxidation rate and highest activation energy. After oxidation at 900 ℃, the alloy substrate and Al coating formed Al2O3 protective film, represented some high-temperature oxidation resistance. After oxidation at 1000 ℃, the alloy substrate emerged lots of microcracks and holes in the surface layer with serious internal oxidation and nitridation phenomena, resulted in a poor oxidation resistance. The Al2O3 protective film of Al coating took on the less surface spallation, more pure and continue, exhibited more excellent high-temperature oxidation resistance.

Aircraft anti-skid brake which is usually installed on the wheels of the main landing gear of aircraft, is a key subsystem to ensure the safety of aircraft takeoff and landing. At the state of aircraft taxiing, the anti-skid braking system will cause the landing gear vibrating forward and backward along the aircraft speed direction, such low frequency vibration is also called walking. This paper established the model of aircraft braking system with the help of MATLAB/Simulink software, the data interaction between the model and the multi-body dynamic model of landing gear is conducted through the joint simulation interface, the walking characteristics is then studied. In order to study the vibration influence of the anti-skid control system, a reference rate velocity difference brake control law with bias pressure bias modulated regulation and a slip rate brake control law based on PI were designed respectively. The influence of key control law parameters on walking vibration is then analyzed on dry and wet runways. Simulation results show that for the two different control laws, the influence of proportional stage parameters on walking and braking efficiency is greater than that of integral stage parameters. In addition, the proportional level parameters vary linearly with braking efficiency and buffeting amplitude within a certain range.

This paper develops a design software for the solar radiation calculation and analysis problem in solar-powered aircraft design process, which can carry out various types of aircraft modeling, laying solar battery panels, solar radiation characteristics in any region, any season, any time and any attitude, single-point verification, radiation of all time flight, etc.

Using rocket sled test to carry out short-range radar acquisition test is an important means to test the acquisition speed and anti-jamming performance of short-range radar at real speed. The radar is placed on the upper part of the rocket sled, and a large deflection will occur when the rocket sled runs at high speed. The vibration sensor is installed at the position of the radar transmitting antenna to calculate the whole swing through integration, so as to ensure that the radar lobe covers the captured body in the sliding process. The purpose of this study is to eliminate the system error through zero compensation, reduce the influence of low-frequency signal on quadratic integration through low-frequency attenuation algorithm, and eliminate the system random error through the adaptation of empirical mode decomposition (EMD) to non-stationary signal. The results show that through the above algorithm, the peak deviation of position data obtained from acceleration integration is less than 5%, which meets the needs of engineering. These innovative algorithm combinations can be applied to other occasions that need to obtain velocity and displacement from acceleration data integration, which is of great significance.

In this paper, based on the structural characteristics of air turbine starter itself, a high-precision finite element model of the whole engine is established by adopting the step-by-step modeling and confirmation method of the structural dynamics of the whole engine. Transient dynamics simulation calculation of a certain type of aviation air turbine starter is carried out under normal and abnormal conditions, so as to obtain the characteristics of vibration influence that may be brought by abnormal conditions with assembly deviations. The mechanical state and dynamic characteristics of bearing cages are quantified and compared, and the results show that the deviation of double gear assembly is one of the main reasons for the breakage of turbine end-supported bearing cages, while the change of bearing preload and eccentric assembly in a limited range of turbine angles have relatively little influence.

Current requirements for future helicopters proposed by some main investigation projects need helicopters to fly at a higher speed than they commonly achieve while maintaining significant hovering performance. In recent years, interests have increased in the study of high speed helicopters, for example, tiltrotor, compound and coaxial helicopter. They have overcome the flight speed of common helicopters. A main characteristic of high speed helicopters is that they have high advance ratio. The main rotor operates over a wide speed range from 100% in hover to 80% in high speed cruise. Main methods to achieve high advance ratio are variable rotor diameter technique and variable rotor speed technique. The former is realized by change the diameter of rotors. The later is realized by changing the transmission ratio or engine rotating ratio. The paper provides a summary of the research on the variable rotor diameter firstly. There are three kinds of methods to change the rotor diameter. Then, the variable rotor speed technique is described, consisting of the development history, large development plan and implementation challenge. Finally, a prospect of the development for the high advance ratio implementation method in the future is made.

In order to improve aircraft transport efficiencies, reduce fuel consumption, utilize secondary energies or external energies, three research directions have been determined by the aviation industry in recent years. Energy harvesting technology is one of them. Energy harvesting is the process by which kinetic energy, solar and so on can be converted to usable electric energy. The ultimate objective is to develop self-powered sensors, actuators, or power other small electronic devices. The vibration caused by the engine and rotor blade is a common energy source for helicopters. It may be converted by piezoelectric effect. An advantage of the piezoelectric energy harvesting (PEH) technology is that it can harvest energies in a larger frequency band. The application is simple. Many researchers have utilized the piezoelectric effect to develop vibration energy harvesting devices. The material selection, energy harvesting and storing system, as well as applications of piezoelectric energy harvesting technology in helicopters is introduced. A prospect of the development for its application in aviation in the future is made.

While laser-printed metals do not tend to match the mechanical properties and thermal stability of conventionally-processed metals, incorporating and dispersing nanoparticles in them should enhance their performance. However, this remains difficult to do during laser additive manufacturing. Here, we show that Nickel-based superalloy reinforced by nanoparticles can be deposited via laser melting of nanocomposite powders. Laser deposited nanocomposite materials have high hardness, high Young’s modulus and excellent ultimate tensile strength performance in almost all laser printed Nickel-base superalloy. The improved performance is attributed to a high density of well-dispersed nanoparticles, strong interfacial bonding between nanoparticles and matrix, ultrafine grain sizes and dislocation regulation enhancement mechanism.

Membrane-type acoustic metamaterials (MAMs) are lightweight materials with excellent low and medium frequency acoustic properties. The typical MAM array process involves using the original single cells as-is. However, practical applicatiossns often require adjusting the size of the cells to fit the actual array area, and few studies have investigated how to determine the appropriate cell size for a given array area. In this study, we selected the spider web model, which has good noise reduction properties at low and medium frequencies between 80–1600 Hz, for array analysis. We investigated the effect of denser arrays on the noise reduction performance (sound transmission loss, STL) of the spider web MAM by comparing the STL of 1 × 1, 2 × 2, and 3 × 3 array models with the same area. Simulation results showed that as the array density increased, the frequency range where the peaks of the STL occurred tended to expand. In the 2 × 2 array model, the free frame contributed to anti-resonance, resulting in a significant high noise reduction region below 700 Hz. This study contributes to the determination of optimal density for practical MAM applications and provides insight into the problem of scale variation in other acoustic metamaterials during the array process.

The double-swept rotor blade is a new type of blade, and its vortex interference noise level is lower than that of traditional blade. In this paper, the contribution of the cabin noise source of a helicopter is analyzed, and the main gear box vibration and rotor aerodynamic noise are determined to be the main sources. The alternating load at the hub center with double-swept rotor blade is calculated. The vibration load information of the main gear box and the rotor aerodynamic load is predicted. Then the noise level in the cabin is analyzed by the acoustic boundary element method. The result shows that the sound pressure level at passenger’s ear is 131dB in the cabin without interior trimming. The skin is determined to be the key structure affecting the cabin noise by the analysis of plane acoustic contribution. After that, four skin structures are designed and their noise reduction effect is analyzed. The metal honeycomb sandwich skin structure has the best noise reduction effect, which can effectively reduce the cabin noise by 10.6%.

During the maintenance and adjustment process of a helicopter blade returning to the factory, the dynamic balance parameters are often deviated and the blades cannot be delivered to users on time. In this paper, the influence of dynamic balance deviation on blade static stiffness properties and airframe vibration level are studied by means of simulation and test. The research shows that the maximum difference of the static stiffness properties between the dynamic balance deviated blade and the qualified one is 7.62%, which appears at the torsional stiffness. The maximum vertical vibration at the key airframe parts of the helicopter equipped with the deviated blade is 0.19g, and the pilot reflects the body feeling well. From the perspective of static stiffness property and airframe vibration level, the dynamic balance deviated blade can be delivered for use.

The paper designs a sliding mode variable structure control (VSC) system for resonant fiber optic gyroscope (RFOG). We have derived the state equation of the control system, given the design process of sliding mode variable structure control system, compared the step response of the control system under different control laws by simulation. The sliding mode variable structure control method is applied to the RFOG control system for the first time, the system static testing is performed using different control laws. The result shows that the VSC method can be well applied to the RFOG closed-loop frequency locking control system, compared with the traditional PID control method, the frequency locking accuracy of the RFOG control system is improved by about 18%. It shows that the VSC control method has better closed loop control performance.

Double-swept blades can effectively reduce helicopter rotor blade vortex interference noise. However, they can lead to the deviation of the aerodynamic center and center of gravity of the blade section relative to the pitch axis, and this can pose a risk to aeroelastic stability during high-speed forward flight. Therefore, it is necessary to investigate this issue in depth. Based on the straight blade of a star flexible rotor, a double-swept blade structure was designed and the dynamic characteristics and aeroelastic stability of the straight blade and double-swept blade were compared and analyzed. The effects of parameters such as sweep-forward angle, sweep-backward angle, sweep-forward station, and sweep-backward station on aeroelastic stability were studied. The analysis results showed that the double-swept structure, compared to the straight blade, can reduce the third flap frequency and first torsional frequency of the blade. Additionally, the double-swept blade can improve aeroelastic stability during forward flight when the double-swept blade beam is strengthened. Increasing the sweep-backward angle is beneficial to aeroelastic stability. However, when the sweep-backward station is closer to the blade tip, the aeroelastic stability becomes worse.

Reasonable allocation of the natural frequencies of a blade can help to avoid resonance or excessive vibration within the helicopter's working speed range, thus reducing and controlling the vibration level. For composite blades, the motion equation of the blade was deduced using the Hamilton principle to obtain the natural frequency and natural vibration mode of the blade. Full-scale blade natural frequency tests were carried out on the rotor testing device, and the analysis results were in good agreement with the test results. Based on this, the influence of rotor stiffness parameters on the natural frequency of the blade was studied. The results show that the first lag frequency of the blade increases with the increase of the elastic bearing and blade lag stiffness, which has little influence on the flap frequencies and torsional frequency.

The level of repair analysis plays a key role for aircraft to achieve satisfactory life-cycle cost, in which the maintenance capability, time, cost and other factors should be considered comprehensively. This paper presents a synthesis decision model for aircraft repair level based on the matter-element extension (MEE) method. According to the characteristics of maintenance support system of civil aircraft, both the economic and non-economic factors were considered as inputs for the model. The alternative repair programs were ranked by the MEE method in view of their comprehensive performance. The set value iteration (SVI) combined with anti-entropy (AE) approach was used to eliminate subjective bias during the weight assignment. It is finally shown via demonstration on an example problem that the proposed model is effective and reasonable providing a novel way to evaluate the optimal repair level in the maintenance supporting system of civil aircraft.

The collaborative application of heterogeneous unmanned systems is one of the key development directions in the unmanned battlefield and civil field in the future. However, it involves multiple different platform types, huge scale, and complex interdisciplinary issues, and there is still a certain distance from large-scale applications. This paper uses the system engineering method to analyze the process of collaborative application of heterogeneous unmanned systems and sort out some directions of future development and some key technologies that need to be breakthrough. The process is divided into four parts: demand acquisition, demand analysis, architecture analysis, and platform design. The system engineering method is suitable for the design and analysis of complex systems and conforms to the characteristics of unmanned systems. It can effectively reduce repeated iterations in the design and development process of heterogeneous unmanned system collaborative applications, and improve inheritance.

The future intelligent cockpit's complex components make it challenging to evaluate the efficacy of man-machine cooperative tasks. This paper uses system dynamics and coupling theory to construct a system dynamics model and quantify the effects of equipment, human, and the environment to reveal the evolution law of man-machine efficacy. The coupling relationship and the factors influencing man-machine efficacy are first determined. The construction of the system dynamics model is the second step. Then, using the Delphi method, the expert weights and the improved interval-valued intuitionistic fuzzy—analytic hierarchy process method are combined to calculate the weights of each factor. The coupling degree of the factors is calculated using the coupling degree model and the N-K model. When the equations have been input, the simulations are then performed. The findings show that changes in the degree of coupling have the following effects: during the first seven units of time, the trend of the change in man-machine efficacy value is essentially flat, and from the seventh unit of time on, the change in man-machine efficacy value exhibits significant performance.

Unmanned aerial vehicle (UAV) based relay communication is an important technical scheme for long-distance wireless communications. However, the UAV-based relay communication system is susceptible to co-channel interference. In this paper, to improve the link reliability of the UAV-based relay communication system, a path planning method was proposed for the UAV. First, a two-hop decode-and-forward (DF) relay communication system model was presented, in which the UAV acted as a relay platform between a mobile access point (AP) and a fixed base station (BS). Then an analytical expression of the outage probability of the system was derived. Based on the criterion of minimizing the outage probability, the problem of jointly optimizing the UAV’s heading and flight speed was formulated and addressed by the Nelder-Mead simplex algorithm. The simulation results demonstrated the validity of this proposed path planning method.

As an important part of the power supply system of civil aircraft, the wire splitter undertakes important functions. This paper uses fault tree analysis to give typical failure modes for the wire splitter, and then uses grey correlation analysis to evaluate the importance of each failure mode. Finally, corresponding suggestions are given for the evaluation results. The method is of great significance to improve product reliability.

Maintainability test and evaluation is of great significance to improve aircraft maintenance efficiency and support level. However, at present, maintainability evaluation involves many qualitative measurement indicators such as accessibility, interchangeability, maintenance human quality engineering, error prevention and maintenance safety. However, qualitative indicators rely too much on human experience, resulting in great subjective differences and difficult to form systematic and objective comments. Aiming at this problem, this paper designs a maintainability verification form, which comprehensively represents the importance of the problem by using the frequency and impact of the problem, so as to reduce the human subjectivity.

Aircraft mission reliability is an important indicator to measure its operational capability, which is of great significance to the aircraft’s ability to perform tasks. This paper establishes a mission reliability evaluation method based on operational requirements for the three main factors that affect flight altitude, speed and acceleration, and calculates the flight profiles of multiple mission profiles to obtain the aircraft’s mission reliability, At the same time, the influence of the difference of flight profile on the reliability is considered, which has guiding significance for the reliability evaluation of subsequent aircraft missions.

The Sonic Black Holes (SBH) absorber consists a cylindrical cavity with a set of rigid thin rings. The inner diameters of the rings are gradually decreasing. The sound speed in SBH can be progressively slowed down, then the effective sound absorption performance can be obtained. In order to further improve the acoustic performance of the SBH, the sponges are used as sound-absorbing material in SBH. The sponges of 2 mm thickness are arranged at the bottom and the different ranges of the inner wall of the SBH. The absorption coefficients of the SBH before and after the sponge arrangement are experimentally investigated. The experimental results reveal that the SBH structure is different from the traditional vibration-based acoustic black hole (ABH) structure. The sound absorption performance cannot be improved effectively when the sponge is placed at the bottom of the SBH. However, when the sponge is placed on the inner wall around the bottom of the SBH, the sound absorption performance can be improved markedly.

Aiming at the wing-mounted and hose-drogue refueling platform of tanker, the disturbance of the wake flow field of tanker on the aerodynamic characteristics of the receiver is studied. Based on the patched mesh technology, the mesh of the tanker, the hose-drogue and the receiver are generated respectively and then patched together to reduce the difficulty of mesh generation. By solving the Reynold Averaged Navier-Stokes (RANS) equation, the numerical simulation of the entire flow field of refueling is carried out on the receiver under the influence of the wake flow field of tanker and its engine jet, and the increments of the aerodynamic force and moment coefficient along the flow wise, span wise and height direction of the receiver is obtained. The influence of the wake of tanker on the trim control of the receiver is studied. The finite element method (FEM) is adopted to analyze the aerodynamic loading of the hose-drogue assembly, and the stress and deformation of each element are obtained. Based on the numerical simulation technology of the coupling solution of CFD and FEM, the equilibrium position of the hose-drogue assembly under the influence of the wake field of the tanker is calculated.

In order to obtain the influence of film hole position on the anti-icing characteristics of aero-engine inlet adjustable blade, numerical simulation and experimental investigation was carried out for different film hole structure of the blade. The performance of different film hole position (include the trailing edge, the side wall and the rotating shaft of strut) and blowing ratio on the heating effects of the adjustable blade surface were analyzed, and experimental verification was carried out under ice wind tunnel conditions. The results show that with the increasing of blowing ratio, the temperature of adjustable blade increases gradually. The surface with film holes located at the trailing edge has the highest temperature, which is 315 K. Under the same working conditions of mainstream and hot air, the trailing edge inclined hole structure has the smallest ice thickness among the 3 structures. Based on the calculation and experimental results for anti-icing of different positions film hole structures on the adjustable blade, the inclined film holes at the trailing edge has better heating and icing protection effect.

In view of the airworthiness review requirements of civil aviation regulations on the cooling capacity assessment of civil helicopters, the cooling test technology of civil helicopter power plant and lubricating oil system is studied. The test data under the planned flight subjects are obtained by adding temperature sensors and signals on the helicopter. The measured temperature data is corrected to the temperature correction data under the upper limit of the helicopter's operating temperature according to the formula, and then the temperature correction data is compared with the temperature limit of relevant accessories and materials to obtain the cooling capacity assessment results. The cooling test technology of civil helicopter power plant and lubricating oil system is studied, which provides a reference for the cooling test of various types of helicopters.

Lightning is one of the disastrous weather phenomena affecting the safety of aviation aircraft. It is very necessary to study the spatial and temporal distribution characteristics of lightning in the flight airspace. Based on the lightning observation data provided by the National Lightning Monitoring Network, we analyzed the time and space distribution of lightning in Sichuan and Gansu areas from 2010 to 2019. The results showed that the monthly frequency of lightning presented a single-peak feature, which was mainly concentrated in April-September, with the highest occurrence month from June to August, and the peak of lightning occurrence appeared in July, with 3.61 million times. Lightning rarely occurs from October to March, but it occurs every month. The frequency of lightning occurrence is the most in summer, accounting for 68% of the whole year, spring and autumn account for 19% and 13% respectively; winter is the least, less than 1%. The frequency of lightning occurrence has obvious annual variation characteristics, and the frequency of annual occurrence in high frequency years can reach more than twice in low frequency years. The spatial distribution of lightning in the region has an obvious large value center, which is located in Luzhou, the southern part of the basin. Generally speaking, the frequency of lightning occurrence varies greatly among regions. The frequency of lightning in Sichuan Basin is higher than Panxi area, and the western Sichuan Plateau is the least. The frequency of lightning activity is relatively consistent with the heavy precipitation in the region, and the precipitation from the western to the southern Sichuan Basin is relatively large, which also corresponds to the most active area of lightning, which has a good consistency.

In this paper, the bidirectional sealing performance of a fixed ball valve in the closed state is studied through the theoretical calculation and finite element simulation. Based on the theoretical calculation model of sealing performance, the results prove that the sealing structure can ensure the bidirectional sealing performance without leakage. At the same time, the contact at the sealing surface is simulated and calculated using Workbench software. The deformation and contact specific pressure distribution on the entire contact surface are obtained. The results show that the deformation gradually increases from the center of the sealing surface to both sides, and the contact specific pressure gradually decreases from the center of the sealing surface to both sides. Reliable sealing circular-bands are formed at the center of the sealing surface in both directions. By reasonably establishing the model, setting boundaries and loading conditions, the simulation calculations are efficient and can obtain more realistic contact specific pressure distributions.

For the problems of implementation difficulty, high cost and low efficient in obtaining the distribution of the infrared radiation characteristics of the dynamic target, the test system and dynamic test implementation method of air targets’ infrared radiation characteristics were introduced in this paper systematically. At the same time, the data processing methods were described in detail for different test equipment. The effectiveness and correctness of the proposed method were verified by flight test. The results show that the infrared characteristic distribution data of the target in the all visual angles can be obtained through the proposed method efficiently and the accuracy were reliable. The method proposed in this paper can support the acquisition of infrared characteristic data of different types of air targets.

This paper aims to perform an optimization of the simulating specimen to search for the optimal specimen design. A design flow chart was adopted and the basic guidelines of the simulating design for the turbine rotor were introduced. The main principle of simulating specimen design is to ensure that the maximum stress and stress gradient at the notch of the specimen are equivalent to the critical part of the component. Then, the genetic algorithm (GA) optimizer capable of optimizing multi-objective was developed combining the ANSYS APDL code. It was found that the vent hole of the turbine front baffle was the critical part. Stress analysis of each individual generated by the GA optimizer was performed and the maximum stress of the specimen was almost the same as the component, reaching 1024MPa. The stress gradient was also compared and showed good consistence with the component. Afterwards, the LCF test of the specimen was carried out and the specimen encountered failure after 150572 cycles. It is 2.18% and 3.36% lower than the predicted results of the specimen and component respectively. It offers a good reference for the LCF life prediction of the turbine rotor.

From the perspective of engineering application, a method to predict the tensile strength of the carbon fiber reinforced polymer (CFRP) was proposed using classical laminate theory and the theory of function of a complex variable. In the method, the influence of defects in the manufacturing process of composite laminates on the tensile strength was considered. The tensile strength of arbitrarily lay-up composite laminate with the same composite material and the same molding process was predicted by the modulus and strength of unidirectional lamina and ultimate strength of a laminate. The method was used to calculate the tensile strength of 5 kinds of composite material systems and 25 types of laminates. The predictions of the present approach were compared to test results. The research indicated that the calculated results were in good agreement with experimental results. Two assumptions about defect treatment of composite laminates can be established. Owing to the current strength theories of composite materials were relatively complicated, the study provided a simple and efficient way to predict the tensile strength of composite laminates for composite structure design.

Aiming at the aerodynamic and structural coupling characteristics between the oscillating blade gust generator system and the wind tunnel body in large low-speed wind tunnel, a coupling analysis system including rigid/elastic gust generator blades, elastic wind tunnel body and flow field aerodynamic force is established. The fluid-solid coupling method is used to analyze the influence of gust generator motion on wind tunnel vibration and gust flow field. The main frequency characteristics of the horizontal and vertical motion direction deformation of the generator blade are obtained. The aerodynamic and structural coupling design and analysis method of gust generator-tunnel system in large low-speed wind tunnel is established, which provides an analysis method for the design of gust generator in large low-speed wind tunnel.

The hypersonic vehicles (HV) represented by the combined powered aerospace vehicle have the characteristics of strong coupling, uncertain aerodynamic parameters, and many control constraints during the ascent phase. The guidance system of HV couple with its trajectory control system strongly and the trajectory optimization and guidance system design process are interactive and complicated. In this paper, a three-dimensional integrated guidance and control algorithm based on dynamic inversion is proposed. The attitude loop controller and guidance controller are designed to establish a mapping relationship between the longitudinal and lateral channel commands and the control surface commands, height and lateral position control of HV can be controlled accurately. The simulation results show that the integrated guidance and control method of HV for the wide-area flight can track reference commands precisely.

The requirements of the integrated standby navigation system based on BeiDou Satellite Navigation System (BDS) are captured and the safety is analyzed. Then, the system interfaces, architecture and three schemes are proposed. In addition, the implementation including hardware and software are introduced. Finally, the test result shows the integrated standby navigation system based on BDS realized in this paper is effective.

Real-time engine condition monitoring requires efficient performance parameter prediction models. Due to the highly nonlinear and dynamic characteristics of the engine, it is difficult to establish a high-precision dynamic engine model according to the laws of thermodynamics. To solve this problem, a method for modeling engine dynamic systems using feedforward deep neural networks with derived features is proposed, and an engine condition monitoring program is written. The method is verified using the full-flight stage data from the aircraft’s fast access recorder, and the results show that the introduction of time-derived features combined with univariate prediction through sliding window data can effectively improve the prediction accuracy of the feedforward deep neural network, even slightly higher than the long short-term memory network of the same structure, and the root mean square error of the prediction of engine performance parameters in the full-flight stage can reach less than 10%. The condition monitoring program enables real-time and offline condition monitoring of the engine through threshold alarms and historical data analysis.

In order to achieve high safety and reliability in the initiation of squibs, this paper designs a high safety aviation squib drive and control system, which mainly includes sensor interfaces, hardware interfaces, software interfaces, and data interfaces. The hardware interface adopts a power output drive method based on inverse time protection to achieve self-recovery and high safety protection of the power drive circuit. The software interface adopts a hierarchical interface fault detection method to identify faults such as squib breakage, terminal output abnormality, achieving accurate isolation and rapid positioning of faults. The data interface uses instruction validity validation to achieve comprehensive processing of instruction data, status data, and BIT data. The experimental results show that the drive and control system has high safety and reliability, which has important practical significance for improving the safety of aircraft systems.

Aiming at the problem that the data communication standards of airborne equipment of different suppliers are obviously different and it is difficult to trace and identify the data transmission between them, it is proposed to standardize the data of airborne equipment based on OSA-CBM standard, create dynamic data models for transmission and static data models for tracing and identification in six functional blocks. In addition, the embedded data processing flow is designed to realize the functions of data acquisition, data processing and state detection in the embedded system. Through instantiation verification of typical embedded equipment on board, evaluate the performance difference between non standardized and standardized embedded equipment data, and verify the interoperability, traceability and identifiability of the data model. It lays a foundation for airborne equipment health management and fault diagnosis, and has engineering application value in airborne embedded equipment condition based maintenance strategy.

The data fusion technology developed in this paper is applied to the remote interface units of aircraft, and by taking advantage of the flexibility and reliability of Zigbee networking, it can quickly interact with other nearby remote interface units with sensor data through Zigbee when a remote interface unit sensor collects interface faults. Therefore, the fault remote interface unit does not need to be degraded in the case of interface failure, and can continue to complete its own control task, so as to ensure the completion of this flight mission.

In this paper, the development history of solar-powered UAV is briefly reviewed, and the technical characteristics and design difficulties of solar-powered UAV are analyzed. Based on the energy conversion process and the design of a solar-powered UAV, the weight design method and process of cross-day solar-powered UAV are given. In the end, some important problems in the weight design of cross-day solar-powered UAV are emphasized, including the calculation of battery weight, the design and realization of light structure and the choice of flight path, which can be used as reference for the subsequent solar-powered UAV design.

Airworthiness provisions are the requirements that must be followed in the development of civil aircraft. In view of the abstract characteristics of airworthiness provisions, a scenario-based clustering model and analysis method for airworthiness provision is proposed, which is applied to the identification of airworthiness requirements in the development process. Combined with the concepts of knowledge clustering and scenario, the requirements of airworthiness provisions are analyzed based on the elements of the scenario, and a provision clustering spatial model is formed. The verification results of selected CCAR 25.951 show that the proposed method is feasible in identifying the applicability of provisions for specific design features.

As the backbone data network of integrated modular avionics system, the reliability of Fibre Channel network has a great influence on the reliability of the system. At present, network reliability allocation only considers hardware devices, which cannot accurately allocate the reliability index of airborne FC network. This paper analyzes the characteristics of FC airborne network and the influencing factors of node reliability, and propose the model and calculation method of FC network node comprehensive importance based on the analytic hierarchy process. By using AGREE method, an accurate network reliability allocation algorithm is designed, and the reliability allocation of non-redundancy and double redundancy FC network nodes is completed. The verification results show that compared with the traditional reliability allocation method, the reliability allocation method in this paper has the advantages of comprehensive factors, high allocation accuracy and strong practicability.

For usage scenes and landing stability of the helicopter, a kind of bionic leg landing gear based on multi-link structure is proposed to replace the original landing gear. The landing gear can effectively improve the helicopter’s complex terrain take-off and landing adaptability. In this paper, the design concept of the bionic landing gear is given, and the research of design and verification technology is carried out. Firstly, based on the six-leg scheme, the structural design of the bionic leg landing gear is given. Then, the drive/control system and the collaborative control method is proposed based on the landing gear structure. Finally, based on this prototype, the tests in laboratory and in real environment are completed for function verification. These research indicate that lightweight design of multi-link bionic landing gear is achieved. And through its drive/control system, the buffering of the landing gear landing process and the stability control of the fuselage are effectively realized. Compared with the traditional landing gear, this kind of landing gear has the advantages of landing attitude adjustment, and complex terrain adaptation.

The trajectory tracking control method of the climbing section of the combined powered aerospace vehicle is studied. Firstly, the configuration of the combined power aerospace vehicle is designed and some parameters are given with reference to the same type of aircraft at home and abroad. On this basis, the longitudinal motion model of the climbing section, the thrust model and aerodynamic model are established. Secondly, the particle swarm optimization algorithm (PSO) and the automatic disturbance rejection control method (ADRC) are combined to design the angle of attack tracking controller of the climbing section. The parameters of the automatic disturbance rejection controller are optimized by using the PSO algorithm. Finally, the simulation of the angle of attack rejection tracking controller is carried out. The simulation results show that the tracking speed of the designed controller is significantly improved, which can effectively reduce the disturbance. Moreover, the controller has a good tracking effect on the input angle of attack command when the aircraft actuator is limited.

In order to solve the tracking problem of hypersonic cruise vehicle (HCV) during high-speed flight, a robust tracking method (CHF) for hypersonic cruise vehicle is proposed. Firstly, the hypersonic cruise vehicle tracking model is established, including a vehicle motion model, a tracking model, a ground-based radar measurement model and a flicker noise model. On this basis, for the nonlinear problem of the system, the tracking method based on deterministic sampling is adopted. Aiming at the noise non-Gaussian problem caused by high-speed flight, a robust tracking method based on Huber-based hypersonic cruise vehicle is proposed. Finally, comparative simulations under various conditions are carried out to verify the effectiveness of the robust tracking method based on Huber. The simulation analysis of the tracking and positioning accuracy of hypersonic cruise aircraft was completed from the aspects of angle measurement accuracy and frame rate measurement. The comparison of CKF and CHF algorithms under different intensity flashes shows the superiority of CHF algorithm in hypersonic cruise vehicle tracking, and higher estimation accuracy and system robustness can be obtained.

Decompression loads play an important role on aircraft interior design and affect aircraft safety. This paper aims at decompression loads resulting from a sudden release of pressure through an opening in compartment with interiors installed. First of all, a calculation model for interior decompression loads was proposed according to the airworthiness requirements and characteristics of air flow. Based on this model, the magnitude and direction of interior decompression loads for a certain aircraft compartment was computed and concluded. Simultaneously its influence on aircraft safety was also analyzed and more critical case was found. The analysis conclusion could be confirmed by checking recording data from 3U8633, an airline with windshield rupture during its flight. Finally, in order to limit the decompression loads at a low level during aircraft interior design, an appropriate total gap was found, which lay foundation on following detailed interior design, including interior gap size definition and gap style design. Accordingly, the aircraft safety was enhanced.

Friction stir weld (FSW) is a novel solid-state welding technique that has gained significant attention in recent years due to its many advantages over conventional welding techniques. One of the potential applications of FSW is in the aerospace industry, where it could replace riveting as a joining method. In this study, we investigated the fatigue crack growth behavior of four different aerospace materials in three different joining methods, including Refilled friction stir spot weld (FSSW) and FSW, and were compared with those of riveted joints. The experiments were performed using MTS fatigue testing machine. The four aerospace materials investigated in this study were 2A12/2A12, 2A12/7A09, 2024/2024, and 2024/7075. The experiments were conducted in three different joining methods, including FSSW, FSW, and riveting. The fatigue crack growth (FCG) rate was determined for each material and joining method by analyzing the relationship between the crack growth rate and the stress intensity factor. The results showed that the crack growth rate decreased significantly when the crack extended to the welding area and riveted hole in the spot and riveting experiments. However, the crack growth rate did not change significantly in the FSW experiment. In terms of different forms of samples, the crack growth rate was higher in the FSSW samples at lower values of stress intensity factor, but it was equal to or greater than the crack growth rate of the FSW samples as stress intensity factor increased. The crack growth rate of the riveting form was relatively stable and higher than the FSSW and FSW samples.

With the popularization of aircraft digitization, PHM (prognosis and health management) of avionics equipment is becoming increasingly important. Due to the difficulty in collecting performance parameters for avionics equipment, we propose a new method, which achieves component-level health assessment based on fault risk. In response to the issue of assessment weight dilution in the system, considering the impact of serial and parallel structures on system functionality, an improved health assessment method based on reliability logic was proposed to achieve system-level health assessment. And then, based on the above, we integrated a health assessment algorithm for avionics equipment. Through example Analysis, the methodology proposed in this paper can effectively evaluate the health status of the avionics equipment population. The analytical health calculation method proposed in this article has a fast calculation speed, which is easily deployed onboard health assessment systems and enhances the health management capabilities of avionics equipment.

Lattice structures fabricated by additive manufacturing such as selective laser sintering (SLS) are promising candidates for lightweight design in aerospace applications due to their superior characteristics such as low density, high specific strength, and specific stiffness, etc. This paper reports an experimental and numerical study on the tensile behaviour of cellular lattices. Nylon 12 lattice specimens, modelled by repeating open-form unit cells consisting of hexagonal prisms, cubic prisms, and triangular prisms are printed via SLS. A finite element (FE) modelling methodology is developed to evaluate the tensile elastic-plastic and fracture behaviour of the lattice specimens. The predicted load-displacement curves and fracture paths are compared to the corresponding experimental results, and the feasibility and capability of the FE model developed is examined.

Speed and oscillation frequency are two key factors that effect tyre lateral dynamic characteristics. Tyre models for previous landing gear shimmy analysis use stationary shape functions for the lateral tyre deformation which eliminate the effects of tyre speed and oscillation frequency. The lateral dynamic characteristics of tyre are studied by test on the dynamometer facility. The variation trend of amplitudes of the tyre self-aligning moment and lateral force with different speeds and oscillation frequencies is observed and fitted based on test results. The tyre model for landing gear shimmy analysis is updated by fitted coefficients. Nonlinear shimmy bifurcation analysis shows the shimmy unstable region enlarges when the tyre speed and frequency effects are considered. The method of updating tyre shimmy model based on test results could be used in landing gear shimmy analysis to improve the analysis accuracy.

In order to solve the problem that the absorption frequency of the traditional honeycomb micro-perforated panel acoustic liner is fixed and can’t be adjusted in the face of complex noise environment, Aero-engine acoustic liner with adjustable sound absorption frequency is to be designed, a single cell in the honeycomb micro-perforated panel acoustic liner is designed and analyzed, and a broadband and telescopic micro-perforated panel sound absorption structure is proposed.Using a structure of micro-perforated plates in series with unequal diameters to expand the range of structural sound absorption frequencies, and achieving the goal of adjustable sound absorption frequencies through a structure designed with telescopic unequal diameters. Simulation results show that it can be tuned in the frequency of 1000–3000 Hz. The acoustic liner design proposed in this paper has a simple structure and strong adaptability in the face of complex noise environment, and has a good engineering application prospect.

The conventional double-degree-of-freedom aeronautical acoustic lining structure is fixed, as is its absorption band range. In view of the problem that the sound absorption band of traditional double-degree-of-freedom aeronautical acoustic linings cannot be offset adaptively with external noise and the sound absorption band is narrow, a parametric improvement study is conducted on the double-degree-of-freedom acoustic lining structure model, and the influence of multiple parameters on the movement of the sound absorption band is analyzed. The theory of a multi-parameter coordinated adjustment method for the movement of the sound absorption band is proposed, and the correctness and feasibility of the proposed method are verified through numerical calculation and simulation analysis. This paper provides a theoretical reference for the adaptive control design of a double-degree-of-freedom acoustic lining structure with adjustable sound absorption bands.

Helmholtz resonators are widely used to reduce narrow frequency band noise. In this paper, an acoustic absorption structure based on Helmholtz resonator arrays is designed, aimed at achieving continuous broadband and low-frequency sound absorption. The basic unit of the structure is a Helmholtz resonator. The acoustic absorption performance was studied by simulation and experimentation. A 3D printed sound absorber was tested in an impedance tube to verify its sound absorption characteristics. The experimental results are in good agreement with the sound absorption coefficient. The results showed that the coupling effect between the double layer cavity and the neck body enhances the sound absorption performance in the low-frequency band. Experiments show that the designed sound absorption structure has continuous broadband sound absorption in the target range of 300–1100 Hz. This study provides ideas and methods for the structural design of broadband acoustic structures.

As hydrogen fuel can realize zero carbon emissions in full life cycle, developing hydrogen-powered aviation is a well-accepted promising alternative option for the aviation industry to achieve the net zero goal in 2050. Hydrogen-powered aviation can choose two different power solutions: hydrogen fuel cells with electric motor (“hydrogen-electric”) or hydrogen fueled turbine engine. Due to high levels of technology maturity and low R&D costs, hydrogen-electric aircraft has developed rapidly, and become the best choice for realizing the rapid application of hydrogen-powered regional aircraft. Worldwidely, there are already two regional aircraft using hydrogen-electric power solutions that have successfully made their maiden flights. The development of hydrogen-electric aircraft cannot be separated from the development of key technologies such as hydrogen storage systems, hydrogen fuel cells, and electric motors. This paper mainly provides an overview and analysis of key technologies research progress of hydrogen-electric aircraft, and finally puts forward expectations for the future development of hydrogen-electric aircraft.

The aerospace industry demands high-performance aircraft structures, which has led to the need for low-cost, effective vibration control methods. In this study, the loudspeaker was modified as inertial actuator for vibration control. Furthermore, the piezoelectric ceramic was integrated into the proposed inertial actuator as sensor. The proposed integrated actuator/sensor overcomes the shortcomings of traditional velocity negative feedback control method. Experimental analysis demonstrates the feasibility and effectiveness of the proposed transducer. Significant vibration reduction can be experimentally obtained in wide frequency range. The control circuit is simple and cost-effective. The innovation of this study lies in the proposal and experimental validation of a novel transducer, which has important implications for improving aircraft vibration performance and provides new ideas and methods for vibration control research in the aerospace field.

The crack on the engine compartment partition of a helicopter continually occurs, which has affected the flight safety. First, the simplified modeling of engine and local structure detail modeling are studied. Then combined with the flight test data and fracture analysis, the high-cycle failure of the structure under the action of aerodynamic pressure and vibration force is analyzed by using the method of frequency response simulation. The average S-N equation is used to improve the design of the original structure. The fatigue damage resistance of the new structure is obviously improved and has infinite life. A new maintenance platform is also designed for the problem of small engine maintenance space feedback from users. The platform not only increases the maintenance space, ensure the safety of staff, but also reduces the probability of accidental damage to the engine compartment partition.

The outbreak of respiratory infections in recent years has given us a sharp reminder of the importance of controlling the air pollutant transport in aircraft cabins. However, currently no effective strategies have been applied to commercial aircraft cabins. Several studies optimized the air-supply parameters of the environmental control systems in cabins, in order to inhabit the spread of the inside pollutant. But the personnel movements often broke the designed airflow patterns, leading to unsatisfactory effects. This study concentrates on applying air curtains to aircraft cabins, in order to better prevent the spread of the air pollutant in the breathing zones of passengers; the air-supply velocity of the proposed air curtains is optimized by CFD as well, to satisfy the design targets which include mean age of air and air velocity near passengers. Results show that the designed air curtains are able to inhibit the transport of air pollutant in breathing zones by both improving the air distribution and accelerating the fresh air flows in aircraft cabins. In addition, the air-supply velocity of the air curtains is also solved to meet the design targets. Efficient optimization of air-supply parameters for the inlets of air curtains in aircraft cabins requires further exploration.

To extend the thermal endurance of the aircraft, a new fuel thermal management system with multi-return flow paths to the fuel tanks (MRFTS) is proposed. Compared with the traditional single return fuel tank system (SRFTS), the biggest difference is the hot fuel can also be returned to the auxiliary tanks in the MRFTS. The flow selector of the MRFTS is equipped with a temperature control strategy, which can keep the system temperature below but approaching the limit values to achieve the acceleration of the waste heat dissipation. And the fuel consuming sequence of the actual fuel tanks has been fully considered in this control strategy. By the numerical calculation of the high-power condition, the thermal endurance of the MRFTS is increased to 3319.8 s while the thermal endurance of the SRFTS is only 389.5 s, which means utilizing the large amount of the heat sink of the auxiliary tanks can significantly improve the aircraft thermal endurance. Furthermore, a mission profile with a long-time aircraft engagement is analyzed as well, which indicates that the MRFTS can control the system temperature not exceeding the limit values by the dynamic selections of the return tanks while the SRFTS cannot meet the thermal management requirements during the engagement stage. Therefore, the MRFTS can extend the aircraft thermal endurance effectively during the entire flight process with the high thermal load.

In order to study the aero-engine thermal management systematically, a steady state simulation program is developed based on the Python language. Through the analysis of the mass and energy transmission characteristics, the overall system can be divided into four subsystems: the main flow channel subsystem (including the compressor, the combustor, the turbine and etc.), the fuel subsystem, the lubricating oil subsystem and the air subsystem. And there is a strong coupling of the working parameters between these four subsystems. The control equations of the flow and heat transfer of each subsystem are established based on the mass conservation principle, the momentum conservation principle and the energy conservation principle. Further, the efficient solving algorithms of the subsystems are proposed, which can guarantee the accuracy and convergency of the solutions. With the joint simulation of these four subsystems, the steady state operating parameters of the whole aero-engine thermal management system can be obtained. The accuracy of the steady state simulation program is validated by the experimental results of an actual turbofan engine. The calculation process can provide some ideas for the subsequent software development.

Under the technical background of testing requirements for laser damage effectiveness evaluation, this project has formed a set of relatively comprehensive optical testing method for evaluating laser damage effectiveness in high-speed wind tunnel from the aspects of optical testing system composition, test layout design, system debugging, parameters setting, data processing, etc., which can comprehensively and effectively meet the testing requirements and complete relevant testing tasks. Starting from preliminary investigation and demonstration, this research delves into the mechanism of laser damage and the macroscopic characteristics of the target, determines the technical route of adopting high-speed photography method, and summarizes the setting rules of photography parameters for different experimental combinations. The research content enriches the technical means and application fields of the current optical testing profession, and accumulates technical experience for undertaking the same type of laser damage verification testing tasks in the future.

In the integrated ejection test of rocket ejection seat, the working state of the seat at the starting stage is an important examination link. Due to the influence of the seat rocket engine plume, the visible light passive imaging technology based on high-speed photography is difficult to obtain the working details of the target mechanism. Aiming at this technical problem, the feasibility study of using range-gated laser active imaging technology to obtain the target image under the plume background is carried out by analyzing the mechanism of the impact of the seat rocket engine plume on optical imaging. The principle of range-gated laser active imaging technology is described in detail, and key technologies such as laser active illumination, range-gated slice imaging, optical signal filtering, and multi-information image fusion are explored. The implementation approach of image acquisition technology is planned to provide research ideas and directions for subsequent technology realization.

This article addresses the control problem for a spin-stabilized guided projectile which is subject to strong couplings, disturbances, and actuator rate limit. The internal uncertainties and external disturbances are lumped as a state, which is estimated by a reduced-order extended state observer. To enhance the decoupling performance, the dynamics related to the inertia, aerodynamic, and manipulation couplings are compensated by feedforward. Further, to alleviate the adverse effect of the actuator rate limit on the control performance, the describing function method is employed to design the feedforward rudder deflection command. Stability margin tester method is proposed to facilitate the tuning process. Finally, nonlinear 6-DOF simulations are performed to validate the effectiveness of the proposed control method.

Based on the homogenization theory, this paper investigates the macroscopic equivalent properties of unidirectional composite materials using a representative volume element model with a typical micro-configuration. A micro-mechanical model of the composite material is constructed considering the periodic boundary conditions. Then the equivalent properties are obtained by the homogenization finite element method. The effectiveness and accuracy of the homogenization finite element method in predicting composite material properties are verified by comparing the predicted macroscopic equivalent properties with experimental values from the literature. Additionally, this paper compares the influences of fiber volume content, fiber arrangement, and mesh density on the macroscopic mechanical properties of the composite material. The results demonstrate that the homogenization method can achieve the correlation of macroscopic and microscopic mechanical properties, which is potentially promising for guiding the new materials development.