Research On Aerodynamic Heat Collection And Conversion Technology Based On Thermal Management Of Hypersonic Aircraft Structure

The hypersonic aircraft faces a severe aerodynamic thermal environment that imposes heavy thermal protection pressure on the aircraft structure.The need for long-term flight in the aircraft leads to a rapid increase in the volume and weight of the on-board power supply,greatly increasing the burden on the aircraft.From the perspective of energy,on the one hand,it is a large amount of aerodynamic heat that needs to be protected externally.On the other hand,the energy burden on the aircraft is aggravated.Therefore,the effective collection and utilization of aerodynamic heat is an important research topic of hypersonic vehicles.Based on the thermal management concept of aircraft structure,this paper designs a new thermal protection scheme that integrates the functions of aerodynamic heat collection and conversion.The core of the program includes two parts:aerodynamic heat collection and aerodynamic thermal conversion.Based on the passive heat protection to achieve high temperature resistance,the aerodynamic heat collection part designs a convective heat transfer structure and a dry ice cooling structure based on the active cooling scheme.Aerodynamic heat conversion utilization is mainly realized in the form of turbine work,and on this basis,the conversion efficiency and output power under different thermal cycle organization forms are studied.In the study of convective cooling structure,the in-depth study on the control effect of internal flow on wall temperature and the heat absorption capacity of working fluid has been carried out.In the case of only considering the cooling of the inflow,the inflow of the inflow to the high heat flow zone is weak,and the heat exchange capacity of the large heat exchange zone is strong.Regardless of the influence of outflow,only when studying the heat absorption capacity of the working fluid,it is found that when the working fluid does not reach the endothermic limit,the mass flow rate is the main factor affecting its heat transfer capacity.When the working fluid reaches the endothermic limit,the inlet temperature and the type of working fluid have a significant influence on the heat absorption capacity.In the research based on dry ice cooling structure,different dry ice cooling structures were designed based on the thermal protection structure of the aircraft.Based on this,the cooling effects of sublimation latent heat cooling and sublimation latent heat+low temperature CO₂ airflow cooling under different structures were studied.In the dry ice area,the heat should be reduced as much as possible to promote the sublimation of dry ice to increase the mass flow rate of the low-temperature CO₂ gas stream.In the cooling zone relying on the airflow,a certain thermal protection structure is required.Based on this conclusion,a dry ice cooling structure with external heat flow is designed for the large-area heat exchange area of the aircraft,which can achieve long-term thermal protection in a large area of the aircraft.In the study of aerodynamic thermal conversion capability,based on the Brayton cycle and the regenerative Brayton cycle,the results of the aerodynamic heat collection part were used to replace the endothermic part of the traditional cycle,and the cycle efficiency and the cycle temperature ratio were studied.The influence of different factors such as cycle pressure ratio and mechanical efficiency on output power and cycle efficiency.At the same time,the influence of the cooling process on the aerodynamic thermal conversion capacity of the working fluid during multiple cycles was studied.It was found that the cooling process has a crucial influence on the aerodynamic thermal continuous conversion capability of multiple cycles.Based on the application requirements of hypersonic vehicles,the scheme of replacing the cooling process with the supplemental gas cycle was discussed.It was found that the low temperature gas-filled circulation can better meet the requirements of continuous circulation under certain conditions.