Numerical Simulation Of Hypersonic Blunt Bodies With Opposing Jet And Cavity Geometric Variations

The problem of drag reduction and heat reduction of hypersonic vehicles has always been a research hotspot.The huge drag will affect the flight speed and efficiency of the aircraft.Strong aerodynamic heating will damage the internal components of the aircraft.When the aerodynamic heating is serious,the structure of the aircraft will even be deformed,leading to flight failure.Therefore,it is very important to carry out research on drag reduction and heat reduction of hypersonic vehicles.This paper uses numerical simulation methods to research the drag reduction and heat reduction effect of the opposing jet of the blunt body by solving the Navier-Stokes equation combined with SST k-? turbulence model.The numerical simulation method was verified by the experimental results in the open literature.The parameter study was carried out using the current numerical method.The effects of parameters such as jet pressure ratio and jet temperature on the flow field structure,surface pressure,surface heat flow and drag coefficient under hypersonic conditions were analyzed.The characteristics of the long penetration mode and the short penetration mode appearing in the flow field structure were analyzed and distinguished.In addition,the concept of unit mass drag reduction and heat reduction efficiency is used,and the effects of jet pressure ratio and jet temperature on unit mass drag reduction and heat reduction efficiency were studied in detail,providing useful information for saving aircraft space and weight.A new method of drag reduction and heat reduction with combination of concave nozzle and opposing jet is studied.This paper analyzes the drag and heat reduction effect of different cavity size and different jet pressure ratio on blunt body at Mach 6.It focuses on the influence of different cavity shape on the structure of opposing jet flow field,the surface pressure of blunt body and the drag of blunt body under different jet pressure ratio.The effects of cavity depth and cavity divergent angle on flow field characteristics and drag and heat reduction effect under different jet pressure ratio are revealed.The results show that there are three kinds of flow field characteristics in the opposing jet flow field under different jet pressure ratio and nozzle shape,long penetration mode,short penetration mode and flow separation flow field characteristics in the nozzle.This paper analyzes the causes of its formation and changes.The results show that the use of a divergent cavity nozzle can significantly improve the drag reduction effect of the opposing jet.It is also found that the use of the cavity nozzle reduces the heat reduction effect of the opposing jet.When the opposing jet pressure ratio is 0.2,the opposing jet flowwith the cavity nozzle can increase the drag reduction effect of the simple opposing jet without the cavity nozzle under the same conditions by about 11%.The research results in this paper provide useful reference information for the design of hypersonic vehicles.