直喷汽油机喷油器射流显微放大特性研究

Characterization of Gasoline Jets from a Single-hole Direct Injection Injector by Means of Microscopic Magnification

在定容弹试验台上,利用高速相机和长距显微镜相结合的方法,研究了不同喷油压力和环境背压下单孔直喷汽油机喷油器射流的显微放大特性。结果表明,汽油射流表面会形成表面波,而且表面波的波长发展具有随机性。间断产生的表面波通常从射流向外摆动的切线处剥离后形成密集的微小液滴群,形成径向分叉的雾化结构。随着喷油压力的升高,射流表面波波长变短,表面波频率提高,导致射流破碎加剧,形成的液滴直径减小。此外,喷油压力及环境背压的升高使射流中相邻径向雾化分支之间的距离缩短。

The characteristics of the gasoline jets from a single-hole direct injection injector were investigated by means of a long-distance microscope and a high-speed digital camera at various injection pressures and backpressures. The results showed that the surface waves were formed along the surface of the gasoline jets, and developed randomly with time. Discontinued surface waves usually broke up at the places where the direction of jet changed and formed dense small droplets. With the increase of injection pressure, the wavelength of the surface wave shortened and their frequencies rose, which promoted the breakup of jets. The distance between two adjacent radial branches of a jet decreased with increasing fuel injection pressure and backpressure.