The flow field simulation and scanning electron microscope observation methods are used to analyze the surface micromorphology of a certain type of turbine blade before and after operation, and the effect of high temperature and high pressure environment on the surface morphology of the blade is investigated. First, in order to improve the calculation efficiency, according to the blade form, a periodic symmetric CFD model of the turbine blade flow field is established, and the temperature and pressure of the flow field are calculated and analyzed by the finite volume method. Then, the surface of the working blade is measured by scanning electron microscope. The morphology is observed to analyze the form of micro-defects on the blade surface. Finally, based on the results of simulation and experimental observations, the reasons for the blade defects and the factors affecting the changes of the blade surface microstructure are analyzed. The results show that the temperature of the leading edge of the blade reaches the highest ${860}\mathrm{\;K}$. Under the combined effect of geometric structure and wave system, the flow characteristics of the flow field near the leading and trailing edge, blade tip, and hub are complicated, and the temperature and pressure distribution in the flow channel is inhomogeneous. The hub near the trailing edge of the blade appears with a cross-grain/inter-grain mixed mode of microcracks about ${180\mu }\mathrm{m}$ in length, and an inclusion crack with a length of about ${30\mu }\mathrm{m}$ appears at the tip of the trailing edge. This is due to the thermal stress of the blade, the metallographic transformation of the blade surface, and the oxidation, hydrogen embrittlement and other effects. According to the actual task of the turbopump, the turbopump ground hot test program should be reasonably arranged, especially in the shutdown stage, consider whether to take atmospheric environmental isolation measures for the cooling of the turbine blades. The current work can provide a reference for the life evaluation of liquid rocket engine turbine blades.

When the power unit of the series hybrid vehicle is overloaded suddenly, the engine torque load rate would be too high, which would lead to abnormally operation. In order to solve this problem, a load compensation strategy based on fuzzy control is designed. By controlling the torque of generator, the engine torque load rate could be regulated, so that avoiding the engine working near the critical condition. The simulation and test results show that the strategy improves the working characteristics of the power unit effectively, makes it operates stable and smoothly until achieve the expected operating point, improves the robustness of the power unit.

Trans-media aircraft refers to a new concept special aircraft with both air flight capabilities and underwater submarine capabilities, which includes submersible aircraft and submarine-launched drones. Aircraft that can span multiple domains is focused on. Through literature research, this study elaborates on trans-media aircraft and their characteristics and applications, introduces in detail the development status of trans-media aircraft at home and abroad, analyzes the technical difficulties of achieving trans-media flight, and summarizes the key technologies required for trans-media aircraft. Finally, based on the investigation and the current development at home and abroad, the prospects of the trans-media aircraft are prospected and development suggestions are put forward.

Aiming at the damage problem of experimental facilities caused by unsteady chamber pressure in experiment of high temperature gas flow wind tunnel, the mechanism of the influence of collector positions and dimensions on the stability of experimental flow field is studied. Study mainly focuses on the interaction between the waves and separated vortexes. Utilizing CFD method, the pressure distribution is obtained in the chamber. Then the relationship between the interaction of the waves and separated vortexes and experimental stability are also explored, which will provide a reference for the optimal design of the collector. The results show that appropriate collector position and reasonable collector dimensions can reduce the overflow in the chamber. It can also avoid the separated vortex dominating the collector port, and increase the flow of mainstream. It is helpful to the conduction of experiment.

In radar countermeasures, the jammer detects the radar signal, then the signal is sampled by AD and input to FPGA for processing and generating interference signal. When using the FFT IP core officially provided by the FPGA platform Xilinx to perform FFT processing on the data output by the high-speed ADC, data preprocessing of "parallel-serial" is required, which greatly slows down the FFT processing speed. At the same time, the internal resources of FPGA is not maximized. An data processing method based on FPGA input block remapping is proposed. This method uses the data input remapping module to optimize the input data into a parallel block data stream format. Then the FFT butterfly networks process the input data into blocks to obtain the discrete Fourier transform data. Finally, parallel data are output. Experimental results show that this method can effectively save FPGA computing time, improve radar data processing speed, optimize the utilization of FPGA internal resources, and has the characteristics of good real-time performance and high flexibility.

Focusing on the main working phase of liquid rocket engine, with the aid of multivariate non-linear time series analysis, and based on Dual Stage Attention Based Recurrent Neural Networks (DA-RNN), a new time series analysis tool, Convolutional Dual Stage Attention Based Recurrent Neural Networks (CDA-RNN), is proposed, by which a fault trend prediction model is established. Compared with LSTM, DA-RNN, etc, this model shows higher prediction accuracy. Combined with autocorrelation analysis of the prediction residual, a quantitative basis of fault detection is proposed after introducing failure confidence probability. Using hot test data with weak fault to validate the model, result shows that the CDA-RNN model enables robust weak fault muti-parameter detection in unsteady working process. This strategy is so effective that it calls for direct engineering application.

The structure of S-shaped cable is complex. When S-shaped cable is separated at high speed, it has large deformation and complex nonlinear contact. The analysis of dynamic deformation and mechanical characteristics of S-shaped cable is one of the difficulties in engineering design. ABAQUS is used to establish the dynamic simulation separation model of separation cable. The dynamic deformation mechanism and mechanical characteristics of S-shaped cable are analyzed, and the correctness of the modeling method is further verified by the ground experiment. The influence of various sensitive factors, such as length, section diameter, tail length and separation speed of S-shaped cable is studied, which can provide analysis method and reference for engineering application.

A product-oriented virtual test framework for structural strength of aircraft bodies is proposed, under which the classical elastic-plastic damage constitutive of materials and general finite element technology are developed, and a human-computer interactive virtual test platform for aircraft cabin structure is created based on the virtual test plug-in tool developed by Abaqus built-in Python software. Using the accurate confirmation technology of step-by-step inspection, the virtual/real test comparison from the specimen to the complex cabin is carried out to verify the feasibility of the virtual test of the cabin structure. The results show that the virtual test can simulate the load-bearing failure of the cabin structure with high fidelity, and the prediction accuracy of the ultimate load-bearing capacity is 4.6%.

There are many capacitive loads in airborne equipment, the safety and stability of power supply are negatively affected by the surge at the moment of switch closing of power distribution facility. The causes and hazards of surge are analyzed, and the scheme of surge restrain is introduced. The parameters of transistor scheme are studied. The experiments of high and low ambient temperature and wide input voltage range are carried out, simulated and tested to verify the function and effectiveness of the design.

The active aircraft defense problem with unknown attacking missile's guidance law is considered, and the one-way and two-way cooperation modes for a target aircraft and a defending missile are introduced. Cooperative guidance laws for the target and defender are proposed by using sliding mode control, which can enhance the measurement observability and meanwhile guarantee the successful defensive interception. A sliding surface is firstly constructed, considering both the requirements of estimation enhancement and successful interception. And then the one-way and two-way cooperative guidance laws are derived, by adopting the double-power reaching law and the state-feedback based exponential reaching law respectively. Compared with one-way cooperative guidance law, the two-way cooperative guidance law is optimized by introducing the cost function of control effort for the target and defender. Meanwhile, in two-way cooperation mode, the target aircraft can take the cooperative maneuver to help defender impact the attacking missile with less control effort. Simulation results show that the proposed cooperative guidance law can guarantee both the good measurement observability and the well defensive guidance accuracy.