Abstract:Aeroengine is a concentrated expression of the national scientific and technological level, industrial design and manufacturing power. High Mach number, high thrust-to-weight ratio and high turbine inlet temperature are the main development directions. The temperature distribution of turbine blades can be revealed through the measurement which is valuable for performance evaluation, failure analysis and turbine blade optimization design. The continuously increasing turbine inlet temperature put forward a higher requirement to the temperature measurement technique in aeroengine. This article primarily introduces three types of contact temperature measurement methods for turbine blade, including thin film thermocouple, crystal temperature sensor and temperature sensitive paint, illustrates the working principles briefly, summarizes the application status at home and abroad, concludes the benefits and drawbacks, and forecasts the development direction of the three temperature measurement methods.

Abstract:The combination of UAV and aerial photography technology expands the mission range of UAV in aerial survey, which is further enhanced by deep learning technology in the ability of intelligent detection. Recently, UAV aerial photography technology has been gradually applied to wildlife protection, which has greatly improved the investigation efficiency. Due to the great difference in characteristics between aerial images and ground images, and the complex background of wildlife living environment, there is no general method that can be directly applied to the detection and statistics of UAV aerial wildlife photography. Firstly, the development of intelligent detection and statistics technology in recent years is reviewed. Then, according to the characteristics of large scene, small target, multi scale and complex background of UAV aerial wildlife photography, the selection and establishment methods of UAV aerial wildlife dataset is introduced, as well as the detection and statistics methods based on deep learning. Finally, the advantages and applicable scenes of these methods are summarized, and the improvement direction is given.

Abstract:Situation awareness is one of the key competencies required by pilots to fly aircraft, and quantitative assessment of pilot situation awareness has been the focus of many studies. To clarify past research on pilot situation awareness, this paper first summarizes six traditional measurement approaches, which include methods such as freeze detection techniques, real-time detection techniques, and post-experimental self-assessment techniques. Then, a mathematical modeling approach is introduced to measure pilot situation awareness, which is more refined and highly predictive. Finally, a detailed summary of the main measures used in past studies of pilot situation awareness is summarized to provide some reference for subsequent research in this area.

Abstract:Through the analysis of the aerodynamic interference of the downwash on wings under different intensities on both sides of the rotor of the composite high-speed helicopter, a certain reference can be given for the design and optimization of the aerodynamic shape of the similar configuration helicopter. Based on the unsteady momentum source method, numerical simulation of the flow field of a composite high-speed helicopter in hovering and forward flight states is carried out, and analysis the aerodynamic effects of different downwash on both sides of the rotor on wings，and study the effect of aerodynamics by changing the height of the rotor disc and the aspect ratio of wing.The results show that: when the composite high-speed helicopter flies forward, with the increase of the rotor disc height, the peak lift difference between the two sides of the wing decreases, and the peak value falls at a lower speed; with the increase of the wing aspect ratio, the lift difference between the two sides decreases. The peak value decreases, and at the same speed after the peak value, the more slender wing, the smaller lift difference between the two sides.

Abstract:In order to improve the effectiveness of the safety assessment of civil aircraft during the operational phase, and to address the problem of the lack of a consistent and systematic process for the onging safety assessment of civil aircraft involving users, the DoDAF was used to design and build a system architecture for the onging safety assessment of civil aircraft based on the Unified Modelling Language from multiple perspectives. The DoDAF framework is based on the Unified Modeling Language to design and build an architecture for continuous security assessment of civilian aircraft from multiple perspectives. In order to solve the problem that the architecture model is difficult to analyse, the complex architecture is abstracted into a complex network, and the node importance evaluation index is proposed in conjunction with the analysis of the centrality and robustness of the complex network to analyse and evaluate the architecture. The results indicate that the proposed method can effectively support the design of the architecture for onging safety assessment of civil aircraft and the analysis of its overall performance.

Abstract:In order to solve the problem that the application of less mature technologies increases the development risk in the development of civil aircraft high-lift systems with high safety and reliability requirements, combined with engineering data, on the basis of airworthiness safety design and analysis methods, a development technology is established. The risk identification method takes a civil aircraft high-lift system as the object, identifies the technical risks affecting its safety, and gives the technical improvement method and risk control strategy. The results show that there are risks in the uncommanded release of the flaps and the uncommanded retraction of the flaps in a high lift system of a civil aircraft. The probability of failure is reduced from 1.656E-09/flight hour to 9.424E-10/flight hour, which meets the system safety requirements and avoids risks.

Abstract:System stiffness (longitudinal, lateral, and torsional stiffness) is a meaningful index for strut nose landing gear design. It arises from profound significance to explore the influence law of system stiffness on shimmy stability for the anti-shimmy design of landing gear. By changing the initial gas pressure of the buffer, the influence of buffer stroke on the system stiffness is analyzed, and the influence of the system stiffness on the initial torsion angle, convergence time, convergence ratio, and stability area of the strut nose landing gear shimmy is studied. Results show that increasing the stiffness of the strut-type nose gear system can improve the anti-shimmy performance, but increase the initial torsional angle and shimmy convergence time, and reduce the ability of the landing gear to resist external disturbances. Therefore, the stiffness of the strut-type nose landing gear system cannot be excessively increased, which provides a guiding significance for its anti-shimmy design.

Abstract:Turbine blade root are commonly processed by grinding, and the grinding process parameters determine the surface quality and fatigue performance. The paper investigated the effect and mechanism of grinding parameters on the surface roughness and hardness of third generation nickel-based single crystal superalloy DD9 based on orthogonal experiment. The experimental results show that grinding surface roughness were mostly affected by the wheel speed vs, followed by the workpiece feed vw, the grinding depth ap had few effects on the grinding surface roughness. The machining hardening appeared at the grinding surface for grinding DD9, the hardening degree were ranged from 1.9% to 13.8%, and the depths of hardening layer were between 60 and 120μm. In order to obtain the small surface roughness, uniform texture and small degree of hardening in grinding DD9 super-alloy, a grinding parameter scope was recommended as, vs ? [20m/s，25m/s], vw ? [12m/min，16m/mim], ap ? [10μm，15μm]. The conclusions provide theoretical foundation for grinding third generation single crystal turbine blade tenon toothe.

Abstract:With the increasing complexity of aviation system, the flight safety accident analysis becomes more difficult. Human factors in safety accidents are often the result of the interaction of multiple sub components in the system. The safety measures can’t be formulated on the basis of a single component. The traditional ATHEANA method is based on the identification of unsafety action and error forcing context to analyze the formation mechanism of human factors. Due to the lack of systematic analysis method, the identification of UA and EFC is often insufficient. Therefore, a hybrid method of ATHEANA-STPA is proposed to analyze aviation human factors. Through the definition of system risk factors and the construction of system control model, we can have a clearer understanding of the process of the accident. Based on the system control model and accident description, the UA is identified within the problem boundary. By comparing the human performance factors, the EFC of UA is discriminated. The formulation of UA control measures is based on the prevention and control of EFC. Through the control of each EFC in the accident chain, the prevention of human factors can be realized, and finally achieve the purpose of accident risk control.

Abstract:In order to improve the calculation efficiency of flight load analysis in the design phase, surrogate models of flight load based on artificial neural network are researched in this paper. The horizontal tail of a turboprop aircraft is studied for example. The input cases and output loads for training and checking are obtained by flight simulation in the full flight envelope according to standards and horizontal tail distributed loads calculation. This paper builds three surrogate models of horizontal tail loads based on BP network, RBF network and ELM network respectively. And the accuracy and efficiency for horizontal tail root section loads prediction of different models are compared. We also conduct quantitative analysis of contribution for input load parameters. The study results show that all three neural network models are accurate, which can greatly improve the analysis efficiency of flight load.

Abstract:Man-aircraft closed-loop characteristics is very important for the high precision flight mission. In order to check Man-aircraft closed-loop characteristics under the condition of shortage of flight test resources ,a visual target tracking system is developed to simulate the control process of high-procision tasks such as air-to-air refueling. Through the virtual target algorithm, the system can simulate air-to-air refueling task, including formation, pre docking, docking, oil transportation and separation. For the virtual air-to-air refueling task function of the system, a new flight test technology is studied, including the flight test method design and the index quantification of man-aircraft closed-loop characteristics evaluation criteria. The target tracking mission system has been successfully applied to a certain aircraft, and successfully demonstrated by using new flight test technology. The flight test results show that the system can realistically simulate the air-to-air refueling task. On the one hand, it can effectively check the man- aircraft closed-loop characteristics, on the other hand, it can effectively train pilots to improve their flying skills of accurate tracking tasks, which has achieved positive effect of optimizing the flight test method, reduicing the risks and saving the costs. The accumulated practical experience is worth popularizing in other types of aircraft.

Abstract:As the main bearing structure of civil aircraft, the fuselage frame is of great significance to the weight of the aircraft. A hoop bending test was carried out on the composite fuselage curved panels with C- and Z-type integral frames to study the failure mode and load-bearing capacity of the integral frame, as well as the influence of lateral support on the load-bearing capacity of the frame. A pair of force couple was used to apply bending load on the panel. The modified engineering algorithms and FE models were used to predict the failure load and compare with the test results. The research shown that C-type integral fame should be selected as the main design plan because of the better design redundancy. The arrangement of lateral support was the key to improve the load capability of the integral frame, as it could affect the failure mode. The modified engineering algorithms could predict the frame lateral stability, effectively, which could be used for calculation iterations of the integral frame size and lateral support ar-rangement, rapidly. However, the engineering algorithm for inner flange local stability was not conservation, and the FE method should be used for optimization iteration.

Abstract:Engine pylon separation is one of the key technologies in civil aircraft design, which is difficult to obtain from abroad. Domestic researches are mainly about theories and thoughts, which cannot be applied on engineering. In this paper, the relationship of design loads among pylon, fuse pin and wingbox is carried out based on airworthiness standards. Load determination methods for strength calculation of interface structures is proposed through scenario analysis. The results show that the engine pylon separation design only needs to consider predominantly upward loads and predominantly aft loads separately. Giving reasonable relationship of design loads among pylon, fuse pin and wingbox can reduce the weight of structures. Load directions of components connecting the pylon to the wing should be determined through scenario analysis considering structural details.

Abstract:The initial preventive maintenance interval recommended by civil aircraft manufacturers usually does not consider the operators’ environment and maintenance capacity difference. It is difficult to achieve the optimal state of availability while meeting the requirements of aircraft safety. For the civil aircraft preventive maintenance interval optimization, the reliability model of components is modified by the age reduction factor to reflect the impact of maintenance work on component performance. Combined with the airlines operation reality, taking component availability as the objective function and reliability threshold as the constraint condition, the preventive maintenance interval optimization model in imperfect maintenance strategy is established. The operation data of air starter is input into the optimal model the results show that the model is reasonable and feasible, which provides a reference for airlines to formulate customized maintenance plan.

Abstract:Aero-engine control system is an important system of aircraft, the uncertainties of control gain attenuation and unmodeled dynamics of aero-engine affect control performance, therefore, a controller combining H∞ adaptive control and compensation control is designed in this paper. Firstly, the H∞ adaptive controller is designed based on the mixed sensitivity theory. Then, based on Lyapunov strict stability theory, the RBF neural network compensation controller was designed to compensate the uncertainty, and the fitting speed was adjusted by the linear function related to the error. Finally, the aeroengine is taken as the controlled object to carry out multi-variable simulation test. The results show that the controller in this paper can effectively compensate the uncertainty and reduce the overshoot and adjusting time compared with the H∞ controller.

Abstract:In the operation of civil aircraft at plateau airport， the climbing gradient is required to be high， and the load loss is serious. Therefore， it is of great significance to optimize the takeoff performance and increase the takeoff weight in terms of economic benefits. In this paper， based on theoretical analysis， the takeoff performance is optimized under the premise of meeting the airworthiness requirements by reducing the flap deflection or using the improved climb method， and the takeoff distances， acceleration stop distances， and takeoff weights of different flap configurations and different climb methods are calculated and analyzed. The results show that the effective optimization can significantly improve the takeoff weight and performance， also yield good economic returns.

Abstract:At present, the quantitative evaluation method of the importance of civil aviation engine customer demand proposed by many scholars at home and abroad does not meet the needs of civil aviation development. Using Kano model and QFD method, this paper proposes an improved algorithm for quantitative evaluation of the importance of customer demand and technical measures, increases the proportion of basic demand in the adjustment coefficient of the importance of customer demand, quantitatively evaluates the importance of customer demand and converts it into quantifiable technical measures for engine products and services, and completes the priority ranking of technical measures.This paper presents the application cases of civil aviation engine operation support system and replacement equipment development. The results show that the improved algorithm for quantifying the importance of customer needs and technical measures can make more scientific and effective resource allocation and decision-making in the process of engine product and service development, and enhance the market competitiveness of products.

Abstract:All sources of power that could initiate unlocking or unlatching of any door must be isolated from the latching and locking systems prior to flight, and the key structural parts of flight must be able to bear the structural limit loads and ultimate loads, and the method of continuous airworthiness event monitoring based on risk management depends on adequate of monitoring data. These airworthiness requirements are interpreted in combination with actual cases, which will be of great help to engineers. Based on this, taking the accident investigation report of United Airlines flight 811 as the blueprint, and according to the current domestic airworthiness regulations and normative documents, this paper used the method of analytical interpretation to study the exposed problems. The results showed that the design of the driving system of the front cargo compartment latch of flight 811 did not meet the airworthiness requirements that it was necessary to disconnect the latch before flight and could not restore power to the cabin door during flight; The design of L-shaped anchor for the front cargo hold door of flight 811 did not meet the requirements of load design and verification in airworthiness regulations; The FAA made mistakes in its assessment of the safety impact and airworthiness risk level of the opening of the front cargo hold door of the aircraft in flight. The content of the article can be used as a reference for aircraft door researcher and aircraft continuous Airworthiness researcher.

Abstract:In the wind tunnel experiment， the existing CPU-based optical flow method takes too long to solve the velocity field of the fluorescent oil film， while the GPU-based optical flow method has the problem of insufficient utilization of GPU resources. To this end， a real-time measurement method of GPU fluorescent oil film motion path based on fluorescent oil film image segmentation and critical constraints is proposed. The fluorescent oil film time-series image is divided into blocks and processed in parallel according to the resources of the GPU， and the corresponding optical flow parallel computing strategy is created， that is， the advantages of the parallel pipeline architecture of the GPU and the shared memory are fully utilized to realize the optical flow calculation of each parallel block. At the same time， combined with the critical constraints between blocks， the number of iterative calculations is controlled by the iterative difference of the speed matrix of each block as a symbol. The experimental results show that the method proposed in this paper is 2 789.5 times faster than the traditional CPU-based optical flow method under the condition of ensuring the calculation accuracy of the velocity field of the fluorescent oil film motion， and the average speed of the GPU optical flow method of the whole frame image is improved. 10.09 times and the real-time solution speed can reach 90 frames per second.

Abstract:The obstacle dataset is a kind of aeronautical information dataset based on the AIXM specification proposed by ICAO under the Aviation Information Management (AIM) system. The query of the obstacle dataset will directly affect the airport clearance assessment and flight procedure design. Based on the analysis of the temporal and spatial attributes of the obstacle dataset, this paper proposes a temporal and spatial-based query method for the obstacle dataset using the spatio-temporal data model and the AIXM specification to solve the query problem of the obstacle dataset. To verify the feasibility and accuracy of the query method, an obstacle query and visualization system is constructed, and random experiments and example applications are designed to validate the method. The validation results show that according to the technique, the obstacles that impact on the airport clearance and flight procedure design can be extracted, and the flight procedure designers" situation awareness of the airport obstacle distribution can be enhanced.