Numerical Study On Hypersonic Aerothermodynamic Of Near-space Flight Vichle

The near space hypersonic flight vichles have the advantage of long range,high speed and high hit accuracy,it has becoming a hot and focal point in national and abroad in recent years.The aero-heating,however,remain a thorny issue because of the turbulent shock-boundary-layer interaction(SBLI),Boundary Layer Transition(BLT),separated flow and rarefied gas flow.This paper considers the comlex conditons mentioned above,then,take some research on the hypersonic aerothermodynamic.The main works are as follows:Firstly,an engineering code is developed to predict the heat transfer of a biconic configuration with angle of attack,and the influence of flow conditions is analysised.Secondly,the scheme effect and grid dependency in CFD are analysised,the results show that the surface heat flux is highly sensitive to the grid system employed in the CFD computations,especially the separated flow.The differences of turbulence model's construction bring about the differences in stagnation point and reattachment position.Thirdly,three dimension HIFiRE-1 configuration is computed,it depicts that the interaction of separation shock and reattachment shock caused the peak heating on the flare.The analysis of influence factors show that,the decreasing of Mach numbers will lead to the shock distance from the wall,as well as the rapid decrease of heat transfer.The decreasing of Renold numbers don't change the structure of flow,but will decrease the heat flux.When we reduce the angle of flare,the separation bubble becomes smaller,and the heat flux decreases rapidly.When we reduce the length of flare until the separated flow can not reattach to the flare,the heat flux decreases quickly,as well.Then,the aerothemodynamic predict method in the rerafied gas flow by DSMC is used,compare with the Navier-Stokes equations based on second order velocity-slip-boundary conditions.The results show that,the CFD adding slip boundary conditions can predict the heat transfer correctly,the same as DSMC method do,however,the former costs lots of calculating resource when the gas is not rare enough,the latter seems to more suitable for engineer prediction.