柴油机喷嘴内部空穴临界初生现象的试验研究

Experimental Research of Critical Cavitation Inception in Diesel Fuel Injector Nozzles

将高速摄影和长工作距离显微成像技术应用在可视化试验台上,开展了喷嘴几何结构对空穴临界初生现象的试验研究。试验结果显示,较小的针阀升程会抑制空穴的出现,较大的喷孔长径比会因为流动损失的增加而使得空穴很难出现,较大的喷孔倾斜角会促进喷嘴内部空穴的出现。同时,通过大量的试验研究,将针阀升程,喷孔长径比和喷孔倾斜角对空穴初生点的影响关系整理得到了空穴临界初生的预测公式,且具有较高的精度。

A flow visualization experiment system with transparent scaled-up injector nozzles, high-speed photograph and long-distance micro-imaging technologies was set up to investigate the effect of nozzle structure on critical cavitation inception. The experimental results show that smaller needle lift has inhibitory effect on critical cavitation inception, and longer nozzle orifice makes it more difficult for cavitation to start due to its larger energy loss. Moreover, larger incline angle of nozzle orifice is good for cavitation to occur. Meanwhile, based on a great many experimental researches, functions that can predict critical cavitation inception in higher precision were developed in which the effect of needle lift, length-diameter ratio and nozzle orifice incline angle on cavitation inception are concluded.