Study On Coupling Effect Between Aerodynamic Flow And Exhaust Plume

Coupling of aerodynamic flow and exhaust plume is the key and difficult point in fluid research for the flow effect of modern hypersonic vehicles.The traditional method for the study of aerodynamic flow and exhaust plume is to ignore the effect of the shock wave effect generated by the aerodynamic shape on the exhaust plume,which is a non-negligible problem for increasingly stringent research precision.At the same time,the stage separation and the coupling of aerodynamic flow and exhaust plume in hypersonic flow are related to shock wave-boundary layer interference,separated flow,and viscous effect,and the related in-depth research is still relatively lacking.In order to develop and improve the calculation method for the coupling of aerodynamic flow and exhaust plume,and to clarify the interaction effect,this paper mainly starts from the following aspects and conducts research of the paper.First,based on computational fluid dynamics,a computational analysis model for aerodynamic flow and exhaust plume flow was established.The boundary conditions,computational grids,and turbulence models were analyzed in detail.The results show that the pressure parameters are less affected by the mesh when the Reynolds number of the near-wall mesh reaches 1.4 in the calculation of aerodynamic flow.When the Reynolds number near the wall reaches 0.019,the heat flow parameters are less affected by the mesh.In addition,three turbulence models k-ε-Rt、k-ε、Rt for research,It is found that k-ε-Rt has good adaptability to the coupling of aerodynamic flow and exhaust plume,while the other two turbulence models have relatively poor convergence and accuracy in the calculation processSecondly,the coupling of aerodynamic flow and exhaust plume of a certain type of missile body are studied in three parts.(a)Coupling of aerodynamic flow and exhaust plume in the presence and absence of missiles.(b)The influence of aerodynamic loads on the structure and parameter distribution of the exhaust plume when the Mach numbers are 0,0.6,4,and 8 respectively.(c)When the attack angle of the projectile is 0°,-0.5°,-1°,how many degree the exhaust plume would deflect.Research indicates,When the missile exists,the shock wave generated by the tail of the missile will have a significant impact on the exhaust plume.As the accompanying flow velocity increases,the initial tilt angle increases and the length of the first Mach wave node decreases.When the angle of attack of the projectile changes from 0° to-1°,the positive deflection angle of the exhaust plume along the Y-axis gradually increases,and the pressure distribution at the bottom of the projectile will exhibit stress concentration.Then,in order to study the stage flow mechanism and the safety of the separation process for thermal separation between the first and second stage of a rocket,a nested grid method was used in combination with a six-degree-of-freedom rigid-body dynamic equation to calculate the dynamic mesh form.The first-stage and second-stage heat-separation processes of multistage rockets are numerically simulated.The results of the simulation of the separation process show that when axisymmetric working conditions are thermally separated,there will be a "rolling" process in the interstage watershed at the beginning of the process.As the inter-stage distance increases,cross-flow and external flow between the stages will increase.Couplings can occur,and the coupling effect can cause the position of the flow separation point on the surface of the upper-level body to change.