Abstract:The aircraft power system technology is one of the core technologies urgently needed studying of new generation aircraft. With the development target trend of more electricity，high efficiency，more cleanliness and intelligence，and less pollution，the technology study of aircraft power system becomes more important，especially for the aircraft new performance requirements of integration，more electricity，interconnection，intelligence and efficiency，the aircraft power system is the significant support for the new requirements. According to the development of abroad power system technology，and proceeding from the high efficient idea of new generation aircraft power system，the concrete scheme of new generation aircraft power system realizing the multi-electric technology，mixture driving technology and power drive technology is introduced，four key technologies and market trend of aircraft power system are analyzed，and the technology difficulties are pointed out. This aircraft power system technology can provide the reference for the design and future development of new generation aircraft study.

Abstract:The giant-size heavy-loaded large airship has the superior advantages at performance and usage to the large transport airplane. This article aims to summarize the state of the art on the world-wide development for the heavy-loaded large airships, emphasizing on their structural characteristics, structural configurations, material selection, structural design and analysis methodology, as well as the design and testing of the reduced scale-model. Some suggestions are put forward to the domestic research and type development of heavy-loaded large airship.

Abstract:Predictive maintenance technique basing on real-time acquisition, transmission and analysis of aircraft data has been a trend in aviation industry. Starting from the technical connotation and systematic function of aircraft maintenance, combining with the research hotspots obtaining from journal articles and patents in this field, we systematically describe the developing status and tendency of predictive aircraft maintenance techniques. Then we sort out the application of new generation of information techniques such as AI, automatic maintenance, autonomous drone, robot, and intelligent supply chain. Finally, basing on the generalization of technical framework and key techniques, we proposed several strategic suggestions for domestic development and localization of predictive aircraft maintenance techniques.

Abstract:It is computationally intensive and time-consuming to perform a large number of CFD simulations in the process of airfoil optimization. This paper develops an airfoil inverse design method using the proper orthogonal decomposition (POD) and back propagation based neural network (BPNN). The optimization process of this method is as follows: First a sample set of airfoil shapes in the design space are generated through Hicks-Henne parameterization, and the flow fields of the sample airfoils are solved by Xfoil and Fluent. Then two POD models of the airfoil pressure coefficients and the geometric shapes are respectively built, and the corresponding base modal coefficients are obtained. Finally, the BPNN is used to map the base modal coefficients of the pressure coefficients to the base modal coefficients of the geometric shapes, in order to achieve rapid prediction of the specified geometric shape under a given pressure coefficient distribution. The results of the test example at subsonic and transonic shows: a two-layer POD+BPNN model based on 200 samples can realize the prediction of the airfoil with target pressure coefficient distribution, and meet the precision requirement of airfoil inverse design.

Abstract:The wind tunnel sidewall boundary layer needs to be controlled since the sidewall interference in the wind tunnel test of the large-thickness airfoil is serious. In this paper，passive vortex generators（VG）are used at first time to control the sidewall interference effect on the large-thickness airfoil FX77-W-400，and two VG-based side?walls interference control configurations are proposed，i.e. sidewall VG and airfoil VG. The effects of the VG installation position on the airfoil aerodynamic performance and pressure field details are studied，and the proper orthogonal decomposition（POD）is used to study the airfoil surface pressure field structure. The research shows that：the passive VG used in this work can effectively control the sidewall interference. The peak suction of the air?foil surface is affected by sidewall VG and airfoil VG. There is a significant linear correlation between the lift coefficient and the peak suction within the scope of this study. The sidewall interference control method used in this work maintains the main structure of the reference airfoil surface flow. The research is of certain guiding significance for the wind tunnel test and theoretical research.

Abstract:Combining the existing slitting tip extension with the noise reduction technique proposed in this paper，based on the 30P30N multi-segment aerofoil, unsteady flow of three-dimensional airfoil structure is simulate by DDES algorithm. Firstly, the pressure and vorticity transient parameters of the model are obtained. And then, the sound pressure level and directivity are studied by FW-H integration method to study the effects of slat cusp geometric extensions on the surrounding flow field and noise characteristics. Finally, based on the instantaneous vortex structure analysis method of ,the generation and evolvement of flow structures in slat cove and corresponding noise distributions are investigated for various extensions. The investigation shows, cusp extension can effectively change the distribution of parameters of slat flow. Among which, extensions along the sheer layer can reduce the strength of turbulence kinetic energy in slat cove and decrease the characteristic dimension of vortices of separating flow, as a result, suppressing the radiation of slat noise (narrow band noise can be reduced by 3dB in low frequencies).

Abstract:When heavy equipment are airdropped, the cabin cross-section is largely blocked, and rapid moving of heavy equipment will cause drastic changes in cabin pressure and even damage the health of cabin crew. Therefore, it is necessary to carry out numerical simulation of the pressure change in the airdrop cabin of the transport aircraft, and to lay a foundation for further research. In this paper, the fluid-solid coupling problem of variable acceleration linear motion in x direction under the combined action of traction pull of parachute, gravity, friction and aerodynamic force in the cabin of transport aircraft is taken as the research object, based on the motion overset grid. Numerical simulation of dynamic pressure variation in the forward compartment of a transport aircraft with heavy load airdrop is carried out. The results show that:(1) the closer the airdrop object from the frontal wall cabin, the higher the flow velocity and the bigger the degree of cabin cross-section blockage, the bigger the dynamic pressure change in cabin, and vice versa. (2) In the wind tunnel test, non-dimensional cabin pressure with reference of the front cabin pressure at the airdrop beginning is the most accurate and appropriate cabin pressure similarity criterion.

Abstract:Operational consequence analysis of system failure is an important branch of aircraft operational reliability analysis, which can provide strong support for cost-benefit analysis of maintenance tasks. In order to study the impact of aircraft system failure on operational consequences and costs, this study starts with the correlation analysis of operational consequences of system failures. Firstly, the impact of aircraft system fault types and release conditions on operational consequences is analyzed. Then, combined with the current practice of airline maintenance and the idea of event tree, a method to support the evaluation of operational consequences and related costs of aircraft system failures is proposed, and the operational consequence and cost assessment model based on aircraft system failure is established. Finally, the feasibility and applicability of the proposed method are verified by taking the fuel system of a certain type of aircraft as an example. The results show that the proposed method is reasonable and effective, which can provide support for evaluating the consequences of failure operation, and provide certain reference for aircraft design, operation and maintenance.

Abstract:In conventional airfoil optimization design method, the aerodynamic performance of the optimal airfoil may deteriorate at the non-design point, so it is necessary to develop the airfoil robust optimization method. This paper develops an airfoil robustness design strategy based on convolutional neural network and polynomial chaos method, which aims to improve the aerodynamic characteristics of the airfoil while improving the aerodynamic stability of the airfoil. This paper first proposes an aerodynamic force prediction method based on a convolutional neural network model; secondly, introduces the polynomial chaos method into the uncertainty quantification link in robust optimization; and then constructs a new method for airfoil robust aerodynamic optimization design. Finally, an optimization design test was carried out on the aerodynamic optimization design problem of the RAE2822 airfoil. The optimization results show that the robustness design strategy of the airfoil proposed in this paper is feasible. After optimization, the aerodynamic characteristics of the airfoil are improved in a wide range of design, achieving the purpose of robust optimization.

Abstract:The sonic boom problem is a great barrier to the application of supersonic aircraft，and the accurate sonic boom prediction method is the key of the sonic boom problem. Waveform parameter method and augmented Burgers equation method are frequently used for the sonic boom prediction. Compared with the waveform parameter method，the augmented Burgers equation method has more complicated model and higher prediction accuracy. To solve the augmented Burgers equation，an effective nonlinear effect solving method is put forward. A far-field sonic boom signature prediction method based on operator splitting method is established，and verified with examples provided by Second Sonic Boom Prediction Workshop（SBPW-2）. The influence of time，space grid density and buffer signal on prediction results are analyzed. The results show that it is unnecessary for the sonic boom solving method to get the required grid density while time and space grid is converged，but to select the suitable grid density ac?cording to practical accuracy demand. The buffer signature does not seem to be necessary for small aircraft such as corporate ones，but for bigger aircraft the buffer signature is essential

Abstract:As an ideal green vehicle, electric aircraft is expected to be widely used in the future. It is a very complicated process for an airplane to run from acceleration to flight to a safe altitude. When calculating the take-off performance of an electric aircraft, it is found that the take-off distance obtained by the approximately uniform acceleration simulation model is always smaller than the actual take-off distance. In order to accurately calculate the take-off performance of electric aircraft, a simulation model of the complete take-off process was established in MATLAB and the error between the model and the actual take-off process was analyzed. By analyzing the change law of acceleration and speed during the take-off process of electric aircraft, a modification function was introduced to modify the Speed in the model. Taking an electric aircraft takeoff performance calculation as an example, the model before and after the modification is used to simulate the takeoff process and compare the calculation results with the flight test data. The results show that the accuracy of the modified model is better than the simulation model before modification, and the simulation results of the revised model are basically consistent with the results of the aircraft flight test.

Abstract:The wingtip can effectively reduce the induced drag, fuel consumption and exhaust emissions, meanwhile, it is eco-friendly and profitable. However, an economic evaluation is necessary before carrying out the wingtip modification project, due to its cost. Based on the Cost-Benefit Analysis, this paper establishes an economic evaluation model of A-type aircraft modified the wingtip, analyzing the influence of the average flight distance, daily utilization rate of the aircraft, the payment method and the discount rate on the wingtip’s ROI. Finally, some case analysis will be given, combined with the evaluation of feasibility and finance, which provides a reference for airlines to modify the wingtip.

Abstract:The manned multi-rotor aircraft has the characteristics of large structural size, large load demand, and variable size and variable number of available rotors. The rapid determination of the power unit of this type of aircraft has strong engineering practicability. This article takes the design of a single-man multi-rotor aircraft as an example, collects data of more than 100 sets of matching schemes recommended by the brand's official website, uses exhaustive calculations and obtains the relationship between nine sets of parameters. Based on this, the rotor and equivalent circuit models are established, and the maximum working voltage of the 22 optimal motors is used to calculate the maximum matching rotor size and the number of rotors required by the optimization formula. The results show that the optimized selection scheme is more accurate and efficient. This method can be used to obtain a power unit scheme quickly with high weight efficiency, high endurance, and low cost, and pave the way for the detailed design of the subsequent manned multi-rotor aircraft.

Abstract:Compared with fixed wings, retractable wings can effectively reduce the waste of aircraft missile bay. The reliability reduction will become a problem that cannot be ignored due to the existence of the kinematic mechanism of the telescopic wing. In order to explore the reliability of the new mechanism, this paper calculates the positioning reliability of a certain type of telescopic wing deployment mechanism from a theoretical perspective, uses Adams to simulate the deployment process of the telescopic wing, combines the Adams/Insight module to calculate the clamping reliability under the friction force, analyzes the reasons for the clamping failure of the telescopic wing. The results show that the presence of foreign matter will significantly reduce the positioning reliability of the telescopic wing, and the main reason for the reduced jamming reliability is the additional torque generated by the upper and lower wing springs at the center of mass of the upper wing.

Abstract:Simulated engine bleed air system is the critical system for large domestic civil aircraft engine airworthiness testings since it is difficult to establish entire physical air consumers. How to simulate bleed air system dynamic characteristic for critical parameters have been become the bottleneck on the development of large domestic civil aircraft simulated engine bleed air system. Based on the method of orifice flow function and Bleed Management Controller, Simulated engine bleed air system is designed and developed. It has been verified by the developed ground testing that the simulated engine bleed air system has good consistency with the technical condition of the prototype aircraft and can meet bleed simulation requirements of part 33. The simulated engine bleed air system can achieve the bleed air temperature, pressure and flow rate regulating and monitoring function .

Abstract:The development of civil aircraft requires the collaboration and support of suppliers, so the choice of civil aircraft supplier is crucial. In order to meet the design concept of modern civil aircraft that emphasizes reliability, maintainability and testability, the article proposes a method for selecting civil aircraft suppliers based on the three indicators.. Firstly, the classification of civil aircraft suppliers is introduced. Secondly, the selection criteria considering different types of civil aircraft suppliers are established, and the subordinate indicators corresponding to each criteria are listed. Finally, the Analytic Hierarchy Process method is selected to establish the selection model of the oxygen system suppliers as well as make expert score simulation, and the importance of the indicators and criteria of different suppliers were obtained. On this basis, the supplier with better performance is selected,thus providing a reference for the selection of civil aircraft suppliers considering reliability,maintenance and testability indicators.

Abstract:In order to solve the problem of oil leakage at the bolted connection of the combustion chamber casing flange, this paper derives the deflection deformation equation of the bolted connection structure by using the analytical method based on the cantilever beam deflection and deformation theory, and establishes a method to optimize the sealing design of the connection structure; the fine finite element of the casing bolted connection is established in ANSYS to calculates the axial clearance of the flange joint surface under different load forms, and the implementation plan to strengthen the sealing performance of the connection is also proposed. Through numerical simulation, the sealing effect of the sealing ring of different thicknesses is clarified, which is to improve the bolt connection of the casing flange, and to provide a reference for oil leakage.

Abstract:At present, the research of Civil Aircraft Atmospheric data system is mostly focused on the atmospheric data computer and the pitot tube aerodynamic characteristics, but the specific atmospheric data module has little research on the effective data of ADS. The influence of atmospheric data module on the pressure pipeline and data precision of civil aircraft is studied, and the structure and performance of ADIRS are analyzed based on the model of pipeline and altitude parameter, the atmospheric test data of the CRJ200 Model DADC, G450 model and G550 model ADIRS are studied. Firstly, the cause of the different error range is found, and then the measured data of three different models are compared, it is concluded that G450 and G550 with ADM can improve the leakage accuracy of aircraft and reflect the air data of civil aircraft in real time. It is found that the design and application of ADM can effectively reduce the layout of the pressure pipeline on the aircraft, save the installation space on the aircraft, reduce the deformation and leakage of the pressure pipeline, and improve the data accuracy of ADS.

Abstract:At present,there are a large number of foreign aircrafts lacking original date in china that need to be refitted,In order to overcome the technical problems of such refitting,Guide the refitting design of the same type of aircraft,Take a foreign aircraft as an example,The design and research of opening reinforcemeng area are carried out, a comparative analysis method of single force element is established to verify the structural strength of the lifting photoelectric pod，The idea of load design is combed,Independently designed the photoelectric pod and lifting mechanism, The stress of each working condition before and after refitting is compared.The results show that,Under the action of airtight pressure,section load and photoelectricity pod load of fuselage,The modified structure can realize the lifting function,Calculaton method and magnitude of load of photoelectric pod are reasonable and credible,The fuselage structure meets the strength design requirements.Results of this study is Successfully applied to an important modification project,The analysis methods of installation of photoelectric pod have important reference value for solving similar problems in the future.

Abstract:High-power aviation airborne electronic equipment will have the problem of over-temperature. Compared with air cooling, the use of the liquid cooling to cool the device has better heat dissipation effect, so the thermal characteristics of the liquid cooling system need to be simulated and calculated. Taking a certain type of airborne liquid cooling as an example, the theoretical calculation model of heat transfer of the main components (such as liquid storage tank, gear pump, radiator, etc.) was established, and the temperature under -40℃~40℃ was simulated and analyzed. The thermal characteristics of the system, and through the state machine programming to achieve temperature control simulation under over-temperature conditions. The results show that the temperature index of this type of airborne liquid cooling system basically meets the technical index requirements of the cold plate inlet temperature (5℃~30℃) under typical working conditions; The fan speed or the control method of opening the ram air port can obviously improve the problem and the cold plate temperature is basically controlled in the range of 5℃~15℃.