Study On Grid Independence In Numerical Simulation Of Hypersonic Aerodynamic Heat For Typical Configuration

Under the condition of high Mach number,hypersonic vehicle will suffer from serious aerodynamic heating problem.Aerodynamic heating will bring the problem of "thermal barrier" to the aircraft,which puts forward higher requirements for the material selection and structural design of the aircraft.In order to provide theoretical guidance and material selection reference for thermal protection,it is necessary to accurately predict the aerodynamic thermal environment.At present,the main methods of thermal environment prediction are wind tunnel test,numerical simulation and engineering methods.With the rapid development of computer,numerical simulation technology has been widely used in the prediction of aerodynamic thermal environment,and the quality of grid is one of the key factors to determine the success of numerical calculation.For the numerical simulation of hypersonic aerodynamics,the importance of grid is reflected in the grid distribution on the surface and in the boundary layer.First of all,the basis of a set of high-quality computing grid is to ensure that there is a solid surface grid that can completely describe the shape of the model.Secondly,the grid distribution in the boundary layer,whether the grid distribution in the boundary layer can capture the change of the temperature gradient is also one of the key points.Based on the above premise,this paper selects three typical hypersonic shapes as the research object,which are ball head,double ellipsoid and lifting body.With the self-developed numerical simulation program as the tool,the grid independence of hypersonic aerodynamic thermal simulation is studied.Firstly,the research status of hypersonic aerothermal numerical simulation is described.On this basis,the importance of grid for hypersonic aerothermal numerical simulation is discussed.Based on the previous research results,three grid factors,namely grid Reynolds number,normal grid growth ratio and grid density,are selected as the research elements of this paper.Then,the numerical simulation program used in this paper is introduced,mainly from the discrete method,flux calculation,time format and boundary condition setting.Based on the two-dimensional cylinder flow experiment,the numerical simulation is carried out.By comparing the numerical simulation results with the experimental data,the effectiveness of the program is verified from two aspects of flow field structure and wall heat flow.Then,taking three typical hypersonic shapes of sphere head,double ellipsoid and lifting body as objects,using the method of single variable,numerical simulation is carried out bygenerating different grid Reynolds number,normal grid growth ratio and grid density on the object surface.The pressure and heat flow results obtained are compared with the experimental values,and three different grid factors are explored for the aerodynamic heat number of hypersonic The influence of numerical simulation,the causes and mechanism of each are analyzed.Finally,through the analysis of heat flow error,the grid independent range of each of them is obtained.The conclusion can provide a reference for the grid generation of hypersonic aerodynamic thermal numerical simulation.Finally,the effects of three grid factors on the numerical simulation of hypersonic aerodynamic heat are summarized.Based on three different shapes,the grid independent range of Reynolds number,normal grid growth ratio and mesh density are concluded.Secondly,the shortcomings of this paper are analyzed and the future work is prospected.