Research On The Structure Design And Simulation Analysis Of Aviation Ejection Seat

Aimed at the problem of pilot's safety escape, based on the mechanism system theory of ejection seat, combined with the methods of theory research, experimentation and numerical simulation, and from the full system of the aero ejection seat, a new technique avenue which could be used to study safety ejection escape was researched.Test, theoretical analysis and numerical simulation are the main methods witch is used to research the technique of the ejection seat system in the word. The test can't obtain the parameters in all attitudes for the limit of test conditions. Theoretical analysis is a method by using mathematical analysis method. But theoretical analysis usually can't achieve a satisfying result. By using CFD, numerical simulation can solve many prominent problems effectively in reseaching ejection seat. And it has became a important method to reseach the ejection seat system in developed country. But in our country, the CFD method is just embryonic.After contrasted and analyzed the technical characteristics of ejection seat system in domestic and foreign, from the pilot's safety protection and degree of damage, a theory of classified protection was proposed according to the pilot's head and neck part, heart and lung part and limbs part. The damage mechanism of ejection overload, braking overload, rotation and high velocity windblast in ejection process were analyzed. The aerodynamic characteristic and stability influencing factor of ejection seat system were provided. Combined with the pilot's physiological characteristics, the endurance index of the pilot was established.The coordinate system of human-seat system was established, and the method of transformation of coordinates was provided. In the process of establishing motion model, the motion was divided into ejection from cabin and free flight according to the basic working procedure of some ejection seat of our country. The acting force between ejection seat and the rail was considered adequately in the phase of ejection from cabin, and the aerodynamic force, the foce from stability devices and the force from drogue parachute were analysed in the phase of free flight. This motion model of the ejection seat system was the base of numerical calculation.The integrated protection CAD model of some ejection seat was established, which included the skeleton model of the ejection seat, the model of pilot and ejection seat model. The model farthest ensured the matching of ejection seat and the human body. And the space position of head, body and limbs of the pilot was simulated very well. Besides, the curved surface modeling technology we used not only ensured the slippery of the surface, but also ensured the accuracy of the main parameter of the human. The structure grid generated by nesting grid technique had high quality and adapted to analysing human-seat system. The N-S equation solver was developed. In the solvor. the windward was applied N-S equation, the space discretization applied finite volume method, the time discretization applied double time step length, and it applied local time step length to accelerate convergence. For the big detached turbulent flow of the wake of the human-seat system, a body-shedding vortex (DES) simulation method of SA(1 epn) was applied, which can increase the calculating speed and precision.The model of human-seat protection system was verified, and there is basic coincidence between the result and the real data. The biggest relative error of calculated result and test result was less than 10%. The model can veritably describe the characteristic of the ejection seat system in ejection process, witch provided a theoretical support for the engineering reseach of the ejection seat.Based on the CAD model of the ejection seat system. The structural strength of ejection seat was analyzed by numerical method. The stability technology and method of the human-seat system were given. And the damage mechanism created by windblast was analyzed. The baffler was designed by the method of numerical simulation, which not only further verified the effectiveness of the protection device, but also established a base for the optimal design of high velocity windblast protection devices.