煤油同轴喷嘴超临界燃烧与火焰特性实验研究

Experimental Investigation on Kerosene Supercritical Combustion and Flame of a Coaxial Injector

为研究煤油同轴离心喷嘴的超临界燃烧与火焰特性以及缩进比对燃烧及稳定性的影响,在煤油超临界条件下进行了不同缩进比喷嘴的燃烧实验,实验采用单喷嘴矩形燃烧室,空气和氧气混合物以气态从同轴喷嘴的中心喷嘴喷注,煤油以液态从同轴喷嘴的离心喷嘴喷注,实验利用采样频率为36k Hz的彩色高速CCD相机成功观测到煤油超临界燃烧现象。煤油同轴离心喷嘴超临界燃烧火焰总体呈圆柱射流状;缩进比较大喷嘴的火焰图像中,喷嘴出口为半透明的"稠密"气状射流,未观测到明显的雾化破碎过程;喷嘴缩进比为1.62时火焰较窄且出现火焰团间歇性脱落情况;缩进比对燃烧和燃烧稳定性均有影响,存在相对最佳值使燃烧较稳定。

The kerosene supercritical combustion and flame has been investigated experimentally using an optically accessible square cross-section rocket combustor operated at supercritical pressure with respect to the critical point of kerosene. Single-coaxial swirl injectors with different recess ratio have been used to inject liquid kerosene and mixture of air and GOx. The flame was directly detected by a high-speed color CCD camera with a frame rate up to 36kHz. The high speed imaging results show that kerosene supercritical flame performed like a round jet stream and when injectors with long recess in use,jet streams near injectors exit looked like dense gas and none atomization phenomenon was observed with adding LED as background. A decreased flame expansion was observed with increasing recess ratio and flame streams periodically broke off as recess ratio equalled 1.62. In addition,the effects of recess ratio on combustion roughness and stability have been investigated. Recess ratio has an optimal range leading to smoother combustion.