Investiation On Key Technologies Of Reducing Drag Resistance And Aerodynamic Heating On Supersonic Vehicle With Opposite Jetting

Supersonic vehicles flying in the near-atmosphere space must deal with the aerodynamic heating and drag force due to strong shock waves,which are the key factors in the development of supersonic vehicle.Opposing jets provide an effective method to reduce the aerodynamic heating and drag.In this study,the molecular dynamics simulation and direct simulation Monte Carlo method are used to calculate the effectiveness of opposing jet from both the macro and micro perspectives.The molecular model of supersonic vehicle is established in this study,and the accuracy is verified by the theoretical formula.With the increase of Knudsen number,the number density and heat flux in stagnation-point increase,and the proportion of supersonic peak in velocity distribution increases,which means the imbalance of shock wave increases.With the increase of the speed of the vehicle,the number density of shock wave decreases,and the imbalance of shock wave is more obvious.When the opposing jet is used,with the increase of the total pressure ratio,the heat flux and drag coefficient decrease,and the collision frequency between gas atom and surface of vehicle.The influence of rarefied gas environment on the effect of opposing jet is calculated by direct simulation Monte Carlo method.When the Knudsen number is small,the flow field structure is the same as the existing research,which proves the effectiveness of this research.The magnitude of reduction of the aerodynamic heating and drag decreased rapidly with the increase in the Knudsen number owing to the decreased volume of the recirculation zone.Moreover,increasing pressure ratio can effectively improve the effect of the opposing jet.However,an excessively large pressure ratio will not only cause the increase in the drag coefficient,but also the decrease in the heat reduction efficiency.Therefore,the pressure ratio should be maintained within a proper range.Furthermore,by changing the parameters of the ejected gas,such as the gas type,jet velocity and temperature,the drag and heat reduction effect of the opposing jet in the rarefied gas condition can be improved.Areospike still have drag and heat reduction effect in rarefied gas environments,and the opposing jet can significantly reduce the heat flux on the surface of the aerodisk.The combination of opposing jet and aerospike can effectively reduce the drag coefficient of the vehicle.