Numerical Study Of Gas Flow For Launching Progress And Design Of The Deflector

Subvertical launching systems have the advantages of wide attacking range and good flexibility,which make them have a good prospect of development.However,gas of high temperature and pressure from engine has multiple impact effects on the stability of the launching system during launching progress.The stability is also the key factor deciding whether the launching would be successful or not.Thus,it is of profound significance for researching the characteristics,the dynamic process and the influence factors of gas flow field thoroughly,as well as optimizing the structure of the deflector.Taking the project of designing a deflector for a kind of experimental launching platform as background,the gas flow field during launching progress was studied in details by means of computational fluid dynamics numerical calculation and experimental verification.At last,an eligible deflector was designed.Simulating the chemical reaction flow,the fluid-solid flow of gas and aluminum particles or sand,as well as designing the deflectors by setting up the surrogate mathematics models are the innovation of the paper.The main work of the thesis is as follows.（1）.The experimental result of jet of high pressure conflicting a platform was taken as a reference.It is considered that the Realizablek-?turbulence model simulate fluid field of gas precisely compared with the standardk-?turbulence model.（2）.Six different conditions with different launching angle of the experimental launching platform without deflector were calculated.The results show that gas would ablate and erode launching system while launching angle exceeds 70°.（3）.A deflector,which is confirmed that it could meet the requirements of guiding the gas and protecting the system,was designed for the condition that the launching angle is equal to 87.5°.The dynamic progress,the solid-fluid coupling effects of gas and sand,as well as the relationship between the structure of deflector and the characteristics of fluid field were studied.（4）.Chemical reacting flow was compared with chemical frozen flow,basing on models of 2D gas conflicting platform and 3D launching experimental platform with deflector.It is found that the temperature of chemical reacting flow in the area of the wall and the mixing layer of jet flow and air,is higher than that of chemical frozen flow,due to the chemical reactions between gas and air.（5）.The fluid field model of a 3D launching experimental platform with deflector was built,considering the solid-fluid coupling effects of gas and Al₂O₃,which is the combustion product of aluminized composite propellant.Results demonstrate that the particle with large diameter would distributes intensively within the core of the jet flow,and the surface of the deflector would be eroded because of high pressure.（6）.Three surrogate mathematic models of the relationship between the structure of deflector and the temperature of the fluid field were set up based on polynomial response surface method,BP neural network method and RBF neural network method.The structure of the deflector was optimized by PSO,and a temperature drop of approximately 400K is obtained through optimization.The accuracy of the surrogate mathematic models was verified by numerical calculation method,and errors are bounded to 1%.