Numerical Study On Flow And Heat Transfer Characteristics Of Combined Transpiration And Opposing Jet Cooling

Because of its extremely fast flight speed and flexible maneuverability,hypersonic aircraft is a comprehensive manifestation of advanced technologies in many fields,and has great strategic significance.The higher the flight Mach number of the hypersonic vehicle,the stronger the aerodynamic heating the fuselage is subjected to,which seriously affects the safety of the hypersonic vehicle.First,a simplified model is established with the leading edge of the wing as the background,and the numerical model of combined cooling is established and verified by using fluent software.Comparing the advantages and disadvantages of transpiration and opposing jet cooling,propose optimized combined cooling structures.Comparing the cooling effects of different combined structures at different Mach numbers,Select the optimal structural form for structural strength and cooling effect.And verify the cooling effect in the actual high-altitude environment.The results show that it has good cooling performance at different Mach numbers,and it is a new type of transpiration and opposing jet combined cooling structure with great potential.Secondly,by changing the inclination angle of the opposing jet slit,porosity and flow distribution,injection rate,flight height and coolant,,to study the effect of different parameters on the cooling effect of the new combined cooling structure.The results show that if the structural material can withstand the increase in coolant injection pressure,the cooling effect is better when the slit expands outward.Increased porosity does not necessarily lead to increased cooling efficiency.In this paper,the small porosity in the front is more conducive to the uniform temperature distribution of the whole structure.The increase in the flow rate of the opposing jet e has a limited improvement in the cooling effect,reasonable flow distribution can reduce cooling waste.The increase of the injection rate can increase the thickness of the isolation gas film,so as to improve the thermal insulation and cooling effect on the wall.The flight height affects the pressure,temperature and velocity distribution of the flow field,under the same cooling conditions,the higher the height,the better the combined cooling effect.Different coolants have different cooling effects under the same mass flow rate,gas with small molecular mass,large specific heat capacity and large dynamic viscosity should be preferred in the selection of coolant.Finally,3D numerical model of the discontinuous slit of the nose cone is established and verified,to study the effect of different interval solid widths and injection rates on the cooling effect of discontinuous slits.The study found that the smaller the discontinuity width,the better the cooling effect,discontinuous slits can further improve the structural strength of the nose cone while ensuring the cooling effect.In high aerothermal environment,the change of injection rate has no effect on the pushing distance of the high temperature zone of the front solid,and the heat transfer from the high temperature region to the solid in front will increase at high injection rates,reducing the cooling effect.Reasonable adjustment of coolant supply according to different flight conditions,which can reasonably reduce the burden on the aircraft while ensuring the cooling effect.