A Study On Impact Load Characteristics Of A Recovery Module Into Water

The instant slamming load of the space return capsule when entering the water under rough sea conditions will cause the structural deformation of the cabin which will cause damage to the capsule structure,the astronauts and equipment within it.More seriously the hull structure may be a failure after the collapse.Slamming is a transient response which can induce high pressure in a short time.As the final step of space flight,the successful and safe arrival of the return capsule is the ultimate symbol of the success of space missions.On the basis of a comprehensive review and summary of the research status and methods at home and abroad,the numerical study of the entry process of the return capsule is carried out based on the Computational Fluid Dynamics(CFD)technology.The specific work and main research results are as follows.(1)Numerical simulations of the slamming process of the three-dimensional capsule are carried out based on the commercial CFD software Fluent 17.2 combined with the finite volume method and the dynamic mesh technology using the VOF model.The velocity of the capsule and the maximum slamming pressure acting on the capsule are obtained and compared with the previous experiments to verify the effectiveness of the numerical algorithm.(2)The three-dimensional numerical wave tanks are established with good accuracy by free surface tracking using user-defined function(UDF).The velocity boundary wave-making method and the damping wave-eliminating technology were utilized.Based on the principle and method of two-way coupled fluid-structure simulation,the problem of return aircraft capsule into still water or wave is studied.The differences between the slamming pressure of the capsule into different conditions were made compared.Results indicate that the peak value of the slamming pressure of the capsule into the wave is smaller than that of one which into still water,while the duration of peak pressure of the capsule into still water is shorter than that of the one into the wave.(3)The three-dimensional numerical simulations are carried out for the water entry of space capsule.The variation of slamming pressure with time is obtained,and the relationship between the acceleration and slamming pressure of the re-entry module is obtained.When the velocity is faster or weight is huge,the slamming pressure will get bigger.(4)The slamming characteristics of the elastic reentry module under waves arenumerically simulated.This paper mainly analyses and compares the trend of velocity change and the relationship between the peak slamming pressure and the velocity of entry in static water and waves for different stiffness of return cabins,and the relationship between the peak slamming pressure and the velocity of entry in static water and waves for elastic return cabins.The peak slamming pressure of the elastic return module is slightly lower than that of the rigid return module,and its velocity variation trend is consistent with that of the rigid return module.The slamming pressure of the elastic return capsule in waves is slightly less than that in still water.