Research On Numerical Simulation Of The Process Of Airspace Vehicles' Ablation Along The Trajectory

When the hypersonic aircraft flight with a large attack angle in the atmosphere for a long time,thermal conditions on the surface is so bad that ablation may appear obviously.The aerodynamic ablation of hypersonic aircraft flying along the trajectory is the key for its thermal protection design.And the key step for solve this difficulty is to predict three-dimensional ablation-temperature field accurately.If you can determine the surface ablation and temperature distribution of the aircraft,it's possible to provide the basis for design accurate thermal structure and evaluate the rationality and reliability of it.The material's ablation process is very complex.The results of aerodynamic thermal analysis are used as the input conditions to solve the ablation problem,while the results of the ablation analysis such as ablation profile,surface temperature of the structure are served as a input conditions for aerodynamic thermal analysis.They are coupled with each other and influence each other.In other words,the ablation calculations are a complex coupling process of several physical field.For three-dimensional ablation problems of the aircraft,the aerodynamic heating and the thermal structure must be coupled with ablative calculation.However,there still has no a single software that can deal with this kind of three-dimensional ablation coupling problem effectively.Thus we need to write program to realize the integration of numerical simulation.Firstly,this paper presents an engineering method for forecasting the surface aerodynamic thermal environment of hypersonic aircraft.The method can calculate aerodynamic heat of the key parts of the surfaces of the hypersonic aircraft,and can gain the three-dimensional distribution of surface thermal environment when aircraft are flying along the trajectory.Then an interpolation method is developed to determine the distribution of aerodynamic heating heat flow of the whole structure.At last,a user subroutine DFLUX is developed to apply the non-uniform heat load.Numerical examples are calculated and the results show that the method described in this article has higher efficiency and precision.Secondly,this paper develops a coupled the three-dimensional numerical method of aerodynamic ablation for the hypersonic aircraft.Element reconstruction technology is proposed to simulate the moving surface due to the ablation,which can be implemented to smooth the ablation moving boundary.And the optimization method is used to optimize the grid quality after reconstruction,which improves the quality of the reconstructed element.And then,an integration method is proposed by coupling the new element reconstruction technology,the aerodynamic heat engineering method,and the ablation model calculation.With this method,the complex multi-physical problems that integrated aerodynamic thermal environment,solid heat conduction and ablation,can be successfully solved for the aircraft along the trajectory.