Coupling Method And Coupling Behaviour Of Hypersonic Flow-heat Transfer And Material Response

Driven by people's pursuit of speed and military requirement,there were positive achievements in various aspects of the disciplinary development and engineering applications in hypersonic technology area,but it also put forward a series of technical problems to be solved.The limitation of understanding of basic science problem,such as hypersonic aerothermodynamics and thermal protection material,hindered the development of relevant key technologies.There are still “unknown unknowns” in hypersonic technology area.The coupled problem between hypersonic aerodynamic thermal environment and material response is one of the key issues.This coupled problem is directly related to the combination property of hypersonic flight vehicle,or even directly determines mission success or failure.The chemical non-equilibrium flow,which contains a lot of oxygen and nitrogen atoms,and the thermal protection material of hypersonic vehicle will experience strong nonlinear interactions,such as hightemperature radiation,ablation,oxidation,and catalysis,etc.The aerodynamic thermal environment affects the thermal/mechanical properties and surface characteristic of the thermal protection material,meanwhile the response of thermal protection material inturn affects the aerodynamic thermal environment.Besides,radiation,ablation,oxidation,and catalysis are coupled with each other,and this makes the complex coupling effect more complex.The coupled problem between the aerodynamic thermal environment and the thermal protection material involves multi-crossed disciplines of physical,chemical,material,heat transfer,and mechanics.The coupled problem has become a key fundamental problem to be solved in hypersonic technology area.However,the research method and test technology for the coupled problem between thermal environment and material response are limited,and the coupling mechanisms of the physical effects(i.e.radiation,ablation,oxidation,and catalysis,etc.)are not clear.With the fast development of hypersonic flight vehicle,the research on the coupled problem of hypersonic flow-heat transfer and material response is eagerly demanded.In this dissertation,the research is concentrated on “the coupled problem of hypersonic flow-heat transfer and material response”,introducing three critical scientific issues,which are “The coupling framework of hypersonic flow-heat transfer and material response”,“The key factor analysis of hypersonic flow-heat transfer and material response”,and “The thermal-mechanical-oxidation coupling analysis of non ablative leading edge”.This dissertation takes the combination of numerical calculation and experimental verification as the research approaches.A coupling method of hypersonic flow-heat transfer and material response is developed,which can accurately predict the thermal environment and material response.This coupling method can provides key technical supports for the development of a new generation of hypersonic flight vehicle.The details are listed as follows:The thesis consists of five chapters.First,Chapter one is the introduction including the background and objective,state of the art and the development of research on the coupled problem of hypersonic flow-heat transfer and material response,the disadvantages existed in the research methods for multi-physics field coupling problem.Finally,the main works of the thesis are outlined briefly.Second,based on the hypersonic chemical nonequilibrim CFD solver,thermal-stuctrual fully coupled FEM solver and reasonable coupling strategy and scheme,multiphysics field coupling analysis is implemented by using partition algorithm.Gas surface interaction model is introduced and finally the framework of hypersonic flow,heat transfer and material response is established.The thesis discusses the results of the established framework validation study by making comparisons between experiments,previous and present CFD simulations.The test cases include: Electre hypersonic flight experiment,tranverse cylinder and UHTC sharp cone.The calculated results are in good agreement with the existing numerical and experimental results to some extent.It is shown that the numerical software has good reliability and precision.Third,a multi-physics field coupling analysis of leading edge has been implemented by using the framework established in last chapter,and ground experiment of UHTC under high specific enthalpy flow in arc jet has been carried out.The results include thermal environment,thermal response of leading edge are obtained.This chapter aslo deals with the results of the experimental-numerical correlations for the characterization of UHTC materials in terms of surface catalicity.Forth,the key factor analysis of hypersonic flow-heat transfer and material response has been conducted by using the framework established in the second chapter.The effects of catalysis,oxidation,ablation and radiation on the coupling heat transfer process are discussed and qualitative or quantitative analyses of these effects are presented.These analyses provide parameters or references for TPS design.Finally,the thermal-mechanical-oxidation coupling analysis of non ablative leading edge has been performed.The effects of dynamic oxidation process of UHTC on the material properties and thermal-mechanical response are studied.The mechanical properties evolution model of UHTC oxide layer are established,thermal-mechanical performance forcasting method for UHTC are obtained.A thermal-mechanical-oxidation coupling damage constitutive relation of UHTC is presented and is inserted into FEM software.Then FEM is coupled to external hypersonic chemical non-equilibrium CFD solver by the multi-physics field coupling framework.By using the thermal-mechanical-oxidation coupling analysis,the temperature jump phenomenon observed in ground tests is explained.