Numerical Simulation Research On Turbulent Flow Field Of Hypersonic Target

When a hypersonic vehicle is flying in the atmosphere,the flow field around the target will generate a plasma sheath,and the resulting "black barrier effect" will seriously affect the electromagnetic scattering characteristics of the vehicle.In-depth study of the formation mechanism of the plasma sheath and the factors affecting the distribution of various parameters in the sheath can better analyze the mechanism of the plasma sheath and the target,and clarify the physical nature of the "black barrier effect".In recent years,studies have shown that turbulence occurs in the flow field around a hypersonic target during flight.The analysis of the target turbulent flow field can further study the characteristics of the plasma sheath and analyze the interaction between the plasma sheath and the hypersonic target.For the simulation of hypersonic target turbulent flow field,in the field of nearby space experiment,this paper establishes a typical hypersonic vehicle geometric model and performs meshing.Based on the principle of finite difference,numerical simulation calculation of laminar flow field and turbulent flow field is performed on the target.The distribution of temperature,pressure,velocity and other parameters in the turbulent flow field of a typical hypersonic target is studied,as well as the distribution of air components in the flow field;in ground experiments,the shock tube can be used to simulate part of the characteristics and study the shock tube A typical target hypersonic turbulent flow field problem.The parameters of the typical target laminar flow field and turbulent flow field of shock tube are compared,and the distribution of air components in the turbulent flow field is given.The radar cross section of the typical target in the shock tube turbulent flow field is researched and analyzed.The main work of this paper is as follows:1.Starting from the basic theories of aerodynamics and computational fluid dynamics,the numerical simulation theory of the turbulent flow field of hypersonic targets is introduced.The main contents include: introduction to common fluid models,physical mechanism of boundary layer separation,physical mechanism of transition from laminar flow to turbulent flow,and control equations describing turbulent motion,commonly used turbulence models,finite difference principle and meshing technology;2.Numerical simulation calculation of the turbulent flow field of a typical hypersonic target.The distribution of temperature,pressure,velocity and other parameters in the turbulent flow field under different working conditions are introduced,and the data on the stagnation point line of the laminar flow field and the turbulent flow field are compared and analyzed.In addition,the influence of different flight conditions on the distribution of flow field parameters is also studied,and the mass fraction distribution of air components in the turbulent flow field is given;3.Perform numerical simulation calculations on the typical target flow field in the shock tube,and analyze and study the typical target radar cross section in the turbulent flow field.Firstly,the working principle of the shock tube is introduced,and then the turbulent flow field results at a certain moment of unsteady motion are intercepted in the simulation results,and the temperature,pressure,Mach number and other parameters are analyzed and compared.Finally,the radar scattering characteristics of typical targets in the turbulent flow field in the shock tube are also studied.