高超声速飞行器逆向射流与层板发汗组合热防护的攻角特性分析

Influence of angle of attack on a combined opposing jet and platelet transpiration cooling blunt nose in hypersonic vehicle

目的:采用层板发汗技术改善高超声速飞行器在攻角飞行时迎风面逆向射流的热防护性能。创新点:1.提出逆向射流与层板发汗组合热防护方案用于高超声速飞行器的热防护;2.采用层板发汗技术改进高超声速飞行器在大攻角飞行时热防护失效的不足。方法:1.设计逆向射流与层板发汗组合热防护钝头体模型(图1);2.通过数值计算方法对比逆向射流与层板发汗组合热防护在不同攻角飞行时的流场结构和激波特性(图6~8);3.通过数值计算方法获得逆向射流与层板发汗的组合热防护特性(图9~12)。结论:1.在攻角飞行时,来流与射流方向发生偏离,且迎风面的再压缩激波增强;2.随着攻角的增加,迎风面受热加剧,且当攻角增加到一定程度时,逆向射流热防护失效;3.采用组合热防护系统时,发汗流的引入可以改善再附区近壁面区域的热环境,从而减少壁面的热流。

Flying condition with angle of attack is inevitable in a hypersonic vehicle,and it may influence the thermal protection system(TPS)performance of opposing jet and its combinations.A 3D Navier–Stokes equation and shear stress transfer(SST)k-ωmodel with compressible correction are employed to simulate the angle of attack characteristics of a blunt body with opposing jet and platelet transpiration TPS.The flowfield and heat flux transfer for angles of attack 0°,3°,6°with jet pressure ratio PR=0.1 and 0°,6°,12°with PR=0.2 are obtained.Numerical results show that the flowfield is no longer symmetrical with the effect of the angle of attack.The flowfield and heat transfer in windward and leeward performed adversely.The recompression shock wave in windward is strengthened,which increases local temperature and strengthens heat transfer.The opposing jet fails in thermal protection when the angle of attack reaches critical value;however,the critical angle of attack can be promoted by increasing PR.Finally,the transpiration gas can strengthen the cooling efficiency of windward,thereby,increasing the critical angle of attack.