Abstract: In order to obtain the effects of nozzle geometry on supercritical fuel injection characteristics， the performances of the supercritical injection of RP-3 aviation kerosene into a quiescent atmospheric environment were experimentally studied by a microscopic shadowgraphy system. The near-field shock structure， condensation length and jet spreading angle affected by nozzle length-diameter ratio were analyzed in detail. The intercepting shock， Mach disk， and condensation phenomenon downstream of the Mach disk were observed during the injection. With the increasing of the nozzle length-diameter ratio， the condensation length， Mach disk diameter and Mach disk distance were all decreased， and maximum reduction was 15.6%， 56.1% and 30.4% respectively， while the jet spreading angle increased， and its maximum increases up to 12.7%.

Key words: Supercritical injection；Length-diameter ratio；Shadowgraphy system；RP-3 aviation kerosene

摘要： 为研究喷嘴构型对超临界燃油喷射特性的影响，采用阴影显微成像系统对超临界RP-3航空煤油喷射到大气环境中的射流特征进行了实验研究，重点分析了喷嘴长径比对喷射扩张角、冷凝长度射流近场激波结构的影响。研究结果表明，超临界燃油喷射时，在喷嘴出口处存在截断激波和马赫盘等激波结构，马赫盘下游会出现工质的冷凝现象，并发现随着喷嘴长径比的增大，射流的喷射扩张角增大且其最大增幅达12.7%，而冷凝长度、马赫盘直径和马赫盘距离均减小，最大降幅分别为15.6%，56.1%和30.4%。

关键词: 超临界喷射；长径比；阴影法；RP-3航空煤油