Numerical Study Of Thermal Environment Of The Earth Reentry/Outer-planets Entry Vehicles

With the rapid development of China’s aerospace industry,we are now among the world’s space powers.Some projects,such as the "manned lunar landing and return","Mars exploration",are put on the agenda.In the process of outer space exploration,it is inevitable to study the aircraft entering the outer planets or returning to the Earth atmosphere,and the high temperature and high pressure flowfield caused by hypersonic seriously affect its flight safety.Moreover,the thermodynamic non-equilibrium effect in the hypersonic flow field is too complex,which causes many difficulties in numerical simulations.This paper mainly uses the numerical simulation technique to simulate the flow field under hypersonic conditions,and then analyzes the aerodynamic thermal correlation problems.The program was set up based on multi-species and multi-temperature conservative equation,including species continuity equations,momentum equation,energy equation,vibrational energy equation and electronic energy equation,etc.The last two equations describe the transportations of total vibrational energy and electronic energy in the field respectively.In this program,the multi-temperature model was adopted to discribe thermodynamic nonequilibrium,which include translational-rotational temperature,vibrational temperature and electronic temperature.The component source terms were adopted to describe the high-temperature chemical reactions.Firstly,the procedure was validated by some classical flight tests or wind tunnel experiments,such as the ELECTRE model flight test,the ball wind tunnel test,the RAM C-II flight test,the Mars reentry vehicle model,and MSL model Wind Tunnel Test,etc.The results show that the program can exactly calculate the thermo-chemical nonequilibrium flow field,and the temperature model has little influence on heat flux and shock detached distance.Secondly,two typical reentry flight corridors were chosen to calculate the high-speed and high-temperature nonequilibrium flow field environment respectively,which contain the Earth reentry FIRE II tester and the Mars enters ball head model.The results show that the pressure(P)is negatively correlated with Ma,the translational temperature(T)and vibration temperature(Tv)are positively correlated with Ma,as well as the low density of the atmosphere at high altitude could affect the variation law of wall heat flux.In addition,the wall catalytic conditions have little effect on the distribution of P,T,Tv and the particle mass fraction in the flow field,but have a great influence on the heat flux value,which shows that heat flux values under super-catalytic wall conditions is higher than that under the non-catalytic wall condition.Finally,use the validated computational program to simulate and analyse some three-dimensional models respectively,such as the Apollo spacecraft model,the HYPULSE wind tunnel model,as well as the MSL vehicle model.The results show that the thermodynamic nonequilibrium effect in the thin-shock layer near the head of the hypersonic vehicle is most significant,and its energy exchanges between the translational-rotational mode and the vibrational-electron mode.Attack angle re-entry causes the flow field to deviate from the vehicle’s blunt head surface,the pressure field will be distributed as eccentric ring,the maximum surface heat flux appears in the lower shoulder,and the stagnation point also transferes.In the 3-dimention model fields,the flow expand rapidly after detouring the shoulders,which causes a large-scale separation whirlpool,and most atoms in the seperation region will be recombined,and the difference between the translational temperature and the vibration-electron temperature in the wake region is very noticeable.The research content has certain practical significance,which can provide some theoretical and technical basis for the development and implementation of the future deep space exploration project.