无反馈通道自激扫掠喷嘴工作特性

Characteristics of a feedback-channel-free self-excited sweeping nozzle

无反馈通道自激扫掠喷嘴仅在压力驱动下,通过两股射流在耦合腔内部的相互作用,就能在出口实现液柱喷射方向的自激发高频变化。为了探索此新型喷嘴在航空发动机内燃油喷射的应用潜力,本研究综合采用高速阴影成像法和二维数值模拟方法,研究了不同工作介质、不同缩比尺寸下,无反馈通道自激扫掠喷嘴的特征流速、工作频率、扫掠张角等参数随工作压降的响应变化情况。结果表明,无反馈通道自激扫掠喷嘴在较宽的工作压力范围(0.1~6 MPa)和特征尺寸范围(0.2~7 mm)内均能够实现稳定的自激发扫掠振荡喷射,产生30°以上的扫掠张角和5 kHz以上的振荡频率。无反馈通道自激扫掠喷嘴的扫掠张角基本不随压力和等比缩放特征尺寸而变化,但是其工作频率与其喉道处的特征流速成正比,与喉道宽度成反比,且其频率响应存在双模态现象。

Feedback-channel-free self-excited sweeping nozzle can generate high-frequency self-excited oscillating liquid spray only driven by the working pressure,through the interactions between two colliding jets in⁃side a dome-shaped cavity.In order to explore the application potential of this new type of nozzle to fuel injection in aero engine,by taking advantage of the high-speed shadow imaging and 2D numerical simulation methods,the nozzle’s characteristic velocity,working frequency,sweeping angle response to the working pressures were comprehensively studied,with various working media and scaling dimensions.The results showed that the feed⁃back-channel-free self-excited sweeping nozzle can generate stable sweeping oscillating spray in a wide working pressure range(0.1~6 MPa)and characteristic dimension range(0.2~7 mm),its sweeping angle was larger than 30°,and oscillating frequency can be higher than 5 kHz.Its sweeping angle keeps stable as the working pressure and scaling dimension vary,however,its working operating frequency is proportional to the characteristic veloci⁃ty at its outlet throat,inversely proportional to its throat width,and represents a bimodal phenomenon.