底部排气法的减阻特性及在超声速导弹上的应用

Drag Reduction of Base Bleed Method and Its Application on Supersonic Missiles

采用数值模拟试验的方法较为系统地研究了底部排气减阻中气流的排出方式、流量消耗率、排气孔孔径和排气孔的收敛或扩张角等因素对底部阻力的影响 ,并将排气减阻的贡献分解为排气冲量和底部压强两部分进行了分析。本文首次将底部排气法应用于导弹上 ,结合一种具有常规气动布局的超声速导弹进行了底部排气方案设计 ,采用一种“底窝器”来提高进气道整流罩的底部压强 ,并进行了风洞实验验证。数值模拟发现 ,研究范围内流量消耗率的增加、排气孔位置的外移、开孔数目的增加以及开孔率的增加均能明显改善其减阻效果 ,但其各自的机理不同。前者主要依靠排气冲量的增加 ,而后三者则主要提高底部压强。风洞实验结果表明 ,“底窝器”能够明显降低全弹阻力系数 ,使全弹阻力系数下降 2 %～ 3 %。

The influence of the key parameters on the drag reduction of the base bleed method is obtained by numerical study. During the analysis the contribution of the base bleed is divided into two parts: the increase of the exhaust impulse and the improvement of the base pressure. Then, the base bleed method is introduced on a general supersonic missile to decrease the base drag of the inlet cowl for the first time and is validated by wind tunnel test. Numerical results indicate that the increase of the mass consumption rate, the outward shift of the orifice, the increase of the orifice number and the increase of the perforation rate can improve the drag reduction performance of the base bleed method obviously, but the mechanisms are not the same. The first one relies on the increase of the exhaust impulse and the other three are owing to the improvement of the base pressure. In addition, the radial jet mode is more effective than the axial jet mode at small gas consumption rate, but the superiority of the axial jet mode shows that the gas consumption rate overruns 0 024. Experimental results of the wind tunnel show that 2%～3% of the drag of the missile is cut down, which is significant to increase the range of the missiles.