Research On The Single-phased And Phase-changed Transpiration Cooling In Supersonic And High Temperature Flow

The heat flux on the hypersonic vehicle surface and engine combustion chamber become higher and higher with the development of aerospace technology.Transpiration cooling has attracted plenty of attention as an effective cooling method.The research topic of single-phased and phase-changed transpiration cooling in the high temperature and supersonic flow is important for the thermal protection for the key components of hypersonic vehicles.There are still several deficiencies in present transpiration cooling system: The transpiration cooling efficiency in the leading edge is lower than other parts;the basic laws of phase change transpiration cooling are not yet clear,and there are problems with the cooling fluid transport and flow control;the mechanical properties of porous materials in transpiration cooling systems still need further improvement.This dissertation systematically studies the above deficiencies and difficulties:In order to improve the cooling efficiency of the leading edge,the combined transpiration and film cooling,combined transpiration and opposing jet cooling for fuel inject struts in Scramjet were experimentally and numerically investigated.The combined transpiration and film cooling had slight influence on the shock waves distributions in the supersonic flow,while the combined transpiration and opposing jet cooling had significant influence on shock waves distributions.Pure transpiration cooling was hard to effectively cool the leading edge of the strut.The cooling efficiency of combined transpiration and film cooling was higher than that of pure transpiration cooling.The combined transpiration and opposing jet cooling with non-uniform coolant injection method could effectively cooling the strut leading edge and the temperature distribution was uniform.In order to explore the basic laws of phase-changed transpiration cooling,the influences of coolant injection ratio and particle diameter on transpiration cooling with phase change was experimentally investigated in the high temperature wind tunnel.The delaying and oscillating phenomenon was discovered and investigated.The average phase-changed transpiration cooing efficiency increased with increasing the injection ratio.Significant delay was observed in the transpiration cooling with phase change.The delaying period decreased with increasing the injection ratio or decreasing the particle diameter.Significant temperature oscillation was observed in the transpiration cooling with phase change.The oscillating amplitude decreased with decreasing the coolant injection ratio or increasing the particle diameter.The oscillating period decreased with decreasing the coolant injection ratio or particle diameter.To solve the problem of cooling fluid transport and flow control in phase change transpiration cooling,a reusable biomimetic self-pumping and self-adaptive transpiration cooling inspired by tree transpiration was proposed and investigated to solve the problems of coolant transport and control.Self-pumping external transpiration cooling and selfpumping internal transpiration cooling were investigated.The self-pumping and selfadaptive effects were experimentally investigated.The mechanism of self-pumping and self-adaptive transpiration cooling was theoretically analyzed.The self-pumping and selfadaptive transpiration cooling is a novel method to solve the problems of coolant transport and control.In order to improve the mechanical properties of transpiration-cooled porous materials,porous plates with reinforcing ribs were manufactured by additive manufacturing method.The influence of coolant injection angle on transpiration cooling efficiency was experimentally and numerically investigated.The transpiration cooling efficiency of the porous plate with vertical micro-holes was higher than that with inclined micro-holes.The transpiration cooling efficiency and mechanical property of porous plate with reinforcing ribs were investigated.The transpiration cooling efficiency of the porous plate with reinforcing ribs was as high as the sintered porous plate,while the mechanical property of the porous plate with reinforcing ribs was significantly higher than that of the sintered porous plate.The paper also studies and reveals the influence of coolant injection angle on transpiration cooling efficiency through experiments and numerical methods.The transpiration cooling module based on 3D printing was designed and manufactured,and the bionic cooling effect of the bionic phase change was studied.