多孔陶瓷氢气发汗冷却特性研究 *

Experimental Investigation of Transpiration Cooling Through Porous Ceramics Using Hydrogen

关键词:  陶瓷多孔材料  发汗冷却  氢气  传热

Key words:  Porous ceramics  Transpiration cooling  Hydrogen  Heat transfer

摘要:

为了研究复合材料微孔发汗冷却热防护技术，研究了冷冻浇注成型工艺定向直孔道碳化硅多孔陶瓷在高压高热流密度时氢气的发汗冷却特性。用电弧加热主流空气产生高温燃气、氢气发汗冷却对多孔陶瓷材料进行了13次热试验研究。试验的材料孔隙率为10～28%，燃烧室压力为3.6～7.9MPa，冷却氢气注入率为0.008～0.021。试验表明，当多孔陶瓷材料氢发汗冷却的注入率为1%时，主流高温燃气与微孔壁面之间的换热减少了30%以上。多孔陶瓷材料氢发汗冷却可以有效减小壁面与燃气之间的对流热流。研究得出了陶瓷多孔材料在高压大热流环境下用氢气发汗冷却的性能关联式。

Abstract:

In order to investigate porous ceramics transpiration cooling performance and potentials using hydrogen as coolant at high pressure and high heat flux，a model chamber was designed and fabricated by reaction bonded SiC with radial directed pore by freeze-casting，which has well oriented pore structure green bodies obtained from a slurry. All the tests were executed in an air arc-heater. Totally 13 hot tests were carried out with 10～28% media porosity，at 3.6～7.9MPa chamber pressure and blowing ratio about 0.008～0.021. The results indicate a significant reduction of heat transfer rate through porous ceramics by hydrogen transpiration cooling. For a blowing ratio of 1%，the local heat transfer coefficient was reduced by about 30% relative to the heat transfer coefficient with no blowing. Some empirical correlations are modified.