Study Of Aero-thermodynamics And Transpiration Cooling

Weapons carried by hypersonic flight vehicle have very important strategic significance for future global military dominance. Therefore, in recent years, the development of hypersonic flight vehicle has become an important tool for competition game between some developed countries, in order to gain an international leading position. However, during the development process of practical application, there encountered key bottlenecks: the aircraft nose cone, leading edge and engine combustion chamber area will face extreme heat flux, which will lead to structure deformation, thermal ablation and other potential dangers. The key to solve these problems is developing new high-temperature resistant materials and more efficient active thermal protection systems (TPS). As a potential active thermal protection technology, transpiration cooling, especially transpiration cooling using liquid water as coolant, has gradually become a hot issue in TPS field for its excellent cooling effect.In this paper, the main research contents include:(1) CFD commercial software Starccm+ was used to simulate the aero-thermodynamic characteristics on aircraft nose cones during supersonic cruise in standard atmosphere. First, distinctions between the aero-thermodynamic environment caused by real near space flight and the test condition of ground arc-heated wind tunnel experiment are compared. Then the nose cone stagnation parameters were investigated, such as temperature and pressure variations with flight altitude and free stream Mach number. Besides, the relationships between heat flux distribution and free stream Mach number were discussed when the secure wall temperatures were specified. Then an example which used liquid water as coolant was simulated, and the consumption of coolant under different flight conditions were shown.(2) Numerical investigations of transpiration cooling on porous nose cone model using gaseous coolant was performed under the condition of high-temperature, low-speed mainstreams by Starccm+ software. The effect of porosity, gaseous coolant species, injection rate, mainstream velocity and mainstream temperature on cooling effectiveness was discussed. Meanwhile, the corresponding pressure difference between inside and outside porous wall was also calculated.(3) In the condition of high-temperature and low-speed mainstream, basic experiments of transpiration cooling using liquid water as coolant on a homemade porous metal plate and transpiration cooling using gas as coolant on a porous nose cone were conducted, respectively. For porous plate model, transpiration cooling experiment was performed in a high-temperature wind tunnel using liquid deionized water as coolant. Infrared thermal image technology was adopted to record the hot side temperature of the plate. Combined with the measurement datas of the chamber pressure sensor and the two thermocouples at different positions of the coolant reservoir, the movement of water phase-change position was monitored under different cooling conditions and the characteristics and principles of transpiration cooling using liquid water were summarized. For porous nose cone model, air was used as coolant. Using the same measuring methods, the influence of mainstream flow rate and coolant flow rate on transpiration cooling effect was investigated, after which relevant conclusions with guiding significance were summarized.