真空条件下多孔平板发汗冷却试验研究

发汗冷却是解决高速飞行器关键部位热防护问题的有效途径。以不同材料的多孔平板为研究对象，以水为冷却剂，利用自行设计搭建的试验平台对多孔平板发汗冷却过程进行瞬态试验测量，得到了不同热流加热环境下不同材料多孔平板内外壁温度变化，并分析冷却剂对不同材料的冷却效果。结果表明:发汗冷却极大降低了多孔平板内外壁温度，起到了有效的主动热防护作用。对于镍、铜金属多孔平板，保持冷却剂水流量约3.5 g/s，在热流密度小于120 kW/m2的条件下，多孔平板内外壁温度稳定在30~50℃。对于陶瓷多孔平板，保持冷却剂水流量约0.32 g/s，在热流密度小于220 kW/m2的条件下，多孔平板内外壁温度基本稳定在30~40℃。在高热流密度315 kW/m2的条件下，对于镍、铜金属和陶瓷多孔平板，发汗冷却时平板内壁温度变化不大，外壁温度分别稳定在约260℃、110℃和130℃。外壁冷却剂处于完全汽化状态，且冷却剂汽化相变位置在多孔平板内部。若无发汗冷却，多孔平板内外壁温度快速升高，其平衡温度较有发汗冷却时大幅提高，进一步表明发汗冷却的巨大应用潜力。 

Transpiration cooling test of porous plate in vacuum environment

During high speed flight, the temperatures of the vehicle can reach extremely high values in the critical parts. To solve the problem of thermal protection for the critical parts, series of transpiration cooling tests using different materials as porous plate and water as coolant were carried out. The experimental platform which was used for the transient measurement in transpiration cooling process was developed. The cooling effects of different material porous plates under different heat flux were evaluated by measuring the inter and outer wall temperature.The results of the experiment indicate that transpiration cooling greatly reduces the temperature of the inner and outer walls of the porous plate, which plays an effective role in active thermal protection. For nickel and copper metal porous plates, the coolant flow rate is kept at about 3.5 g/s and the temperature of inner and outer wall is stable at about 30℃-50℃ when the heat flux is less than 120 kW/m2. And for ceramic porous plates, the coolant water flow rate is kept at about 0.32 g/s, and the temperature of inner and outer wall is basically stable at about 30℃-40℃ when the heat flux is less than 220 kW/m2. Moreover, for nickel, copper and ceramic porous plates, the temperature of the inner wall changes little under the condition of high heat flux of 315 kW/m2 during transpiring cooling, and the outer wall temperature stabilizes at about 260℃, 110℃ and 130℃, respectively. The coolant on the outer wall surface is in a completely vaporized state, and the vaporized phase transition position of the coolant is inside the porous plate. In addition, the temperature of the inner and outer walls of the porous plate rises rapidly when there is no transpiration cooling, and its equilibrium temperature is greatly increased compared with the transpiration cooling situation, which further shows the enormous application potential of transpiration cooling.