The Research On Design And Optimization Method Of Reentry Vehicle Structure

Reentry vehicle is the spacecraft which can bring cosmonauts and space-goods back to the earth, during the process of the reentering, the vehicle enters aerosphere with high speed, it produces huge quality of heat because of the friction with the air around it. So, the reentry environment is terrible, and makes higher requirement of the spacecraft's sturctural. In this article, the method of vary-parameter based on the inverse designing is used, makes the widely used Soyuz class reentry vehicle as the research object, to analyse the aerodynamic force and heating during the reentering, so as to the rule of aerodynamic configuration varying by parameters, establishes the re-entry spacecraft description in the form of multi-objective optimization, to design and optimize the reentry vehicle, finally, finite element method is used to verify the optimization, in order to prove the optimazition to be effective, and provide the basis on the designing of the aircraft. This paper is divided into the following three aspects of work:Based on the structural characters of the Soyuz class reentry vehicle, the theory model is established firstly. Then the reentry environment in every height are solved by introducing the concept of geopotential height. The aerodynamic coefficients, including the lift-drag ratio are solved by panel method. By the Newton second law, the trajectory in longitudinal plane are derived. The Kemp-Riddell formula is used to solve the heat transfer of the reentry vehicle with attack angle or no, so as to the rule of the heat transfer along the outline of the vehicle. From the rules above, it can be concluded the position of the most terrible reentry environment is located at, and proves the air characteristics are varied by the geometry parameters, what's more, it always exalts one characteristic while depresses others'.Based on weakness of the familiar single-objective design optimizations do not meet the request of this target, and the fixed weight genetic algorithm optimizations can not make full use of the search capability, in this article, generally considering the air characteristics, the method of traditional Multi-Objective Design Optimization (MDO) and MDO genetic algorithm are used individually to optimize the figure of the reentry vehicle. Based on the concept of Pareto, the method of improved non-dominated sorting genetic algorithms (NSGA-II) is designed. From the simulation of simple examples, it is proved that NSGA-II method can improve the weakness of uneven Pareto, large computation and low level of population, and make the optimization more quickly and efficiently. And then, this method is used to optimize 6 different aerodynamic configuration, in order to get the best one. From the result compared with weighted objective method, in order to prove that the one based on the NSGA-II method behaves the better aerodynamic characteristics.At last, the analsys based on the finite element method and optimaziton result test is proceeded. Based on the fluid-structure couple phenomenon, and traditional lagrangian or eulaerian methods can't solve this problem efficiently. The arbitrary lagrangian-eulerian method (ALE) is used to solve the fundamental equations of Also, the finite element method based on ANSYS and FLUNET is used to analyze the velocity, pressure and temperature of the flow systems, and the pressure and distortion of the vehicle itself, in order to prove the ALE method is correct. At last, the result is compared with the optimization or no, the result shows that configure optimazed by MDO based on NSGA-II makes the better aerodynamic performance.