Numerical Simulation Research On Surface Heat Flux For Hypersonic Blunt Body

With the increase of the Mach number,the aerodynamic heating of hypersonic aircraft is more and more serious,and how to accurately calculate the surface heat flux of hypersonic aircraft is the premise of thermal protection design.Because of hypersonic experiment is very difficult,In the paper,DNS is performed for two kinds of typical blunt cone flow(ball and stigma)stagnation point and surface heat flux with Mach numbers 4.5,6 and 8,the air parameters adopted the gas corresponding to the altitude of 30 km.To study the influence factors of heat flux,and provide the basis for thermal protection design of hypersonic aircraft.Control equation is the N-S equation in the cylindrical coordinate system.The convective terms are calculated using fifth order WENO schemes.The viscous term used six central difference scheme.The time term is discretized by R-K method.Air treated as perfect gas.The main work of this paper is as follows:1.Based on the two-dimensional governing equations of the hypersonic complete gas in the cylinder coordinate system,in view of the flux adopted different ways of division.For example,the splitting scheme of Steger Warming,Lax-Friedrichs and Feature projection split format,etc.Analyzed and compared the calculation results of three different splitting methods.2.For ball nose cone,the wall boundary conditions of adiabatic and isothermal are used to calculate the steady flow field.For each item in the energy equation were calculated,and the law of energy transfer along the polar axis was analyzed.Findings:(a)For two kinds of boundary conditions,the shock wave satisfy the normal shock wave characteristics,that is,when the fluid through the shock wave,the total temperature is constant,the entropy increase,it is an adiabatic irreversible process.(b)For the adiabatic wall,the stagnation process is isentropic process.(c)For isothermal wall,the heat transfer to the object,which occur near the wall.3.Verify the grid Reynolds number is an important factor on accurate calculation of stagnation heat flux,that is,when the grid Reynolds number is close to 1,the surface heat flux density is no longer affected by the grid size.Also found that heat flux peak with cold wall generally focus on the computational model about 5% of the ball head radius,in addition,the effects of Reynolds number,Mach number,wall temperature and other factors on the heat flux were also studied,similarly,in view of the stigma surface heat flux was calculated and compared the different shapes on the model to the influence of surface heat flux.