Fast Prediction Method Of Hypersonic Thermal Protection Based On Phase Change Heat Transfer And Transpiration Cooling

Hypersonic aircraft is the focus of future national defense strategy.The strong wall effect has caused a huge heat flux on the surface of the aircraft.Temperature-resistant materials can no longer keep up with its development speed.Therefore,an efficient and reliable thermal protection cooling system is required.Transpiration cooling is an active cooling technology with high cooling efficiency.The phase change of the coolant can use the latent heat to further enhance the cooling effect,and use less working fluid.However,the law of phase change flow and heat transfer in porous media is still unclear.The research on the law of phase change transpiration cooling is of great significance to the thermal protection system of hypersonic aircraft.This article will quickly predict the thermal protection system based on phase change model and transpiration cooling technology.Aiming at the key technical problem of phase change heat transfer in porous media of hypersonic vehicle thermal protection system,based on the water vapor RPI phase change model and the porous media non-equilibrium heat transfer model,this thesis develops a solid/fluid coupled heat transfer fast prediction model,which can effectively apply to the rapid design and performance evaluation of advanced thermal protection systems using porous media.It is in good agreement with the model experiment and the calculation results of the CFD advanced phase change model.The physical mechanism of the non-equilibrium heat transfer process of porous media considering the phase change,the strong wall effect of hypersonic flight and the viscous dissipation of high enthalpy flow are further studied.The estimated calculation results show that under certain flight conditions,as the coolant flow rate increases,the cooling efficiency tends to be flat,and due to the phase transition process,the greater the proportion of the phase transition area,the greater the cooling capacity,but the pressure loss also increases.This leads to a more complicated relationship between coolant flow and flow resistance,that is,there is an extreme value of resistance at a certain intermediate flow.The simplified reduced-order model and the calculation result of the porous nose cone are basically the same,but the air intrusion changes the evaporation area.The position of the phase change and the degree of gasification of the working fluid are the main reasons for complex flow and heat exchange and the inhomogeneity of transpiration cooling efficiency.The mass flow,porosity and external heat flow together have a compound effect on it.The model in this thesis can perform relatively accurate dynamic flow control according to flight conditions,and estimate the design parameters of the entire Transpiration cooling thermal protection system in advance.Aiming at the design of the cooling structure of the hypersonic vehicle,the model in this thesis can quickly obtain the relationship between the coolant flow rate,boundary of phase-change region,porosity and thickness of the protective layer by controlling the vaporization process of the coolant and its interaction with the external flow field,and meet the calculation accuracy of the initial design of advanced cooling structure.