喷油嘴空穴流动可视化及其对喷雾的影响  

Visualization of Cavitating Flow in Diesel Injector Nozzles and Its Effects on Spray

作　　者：施东晓 周禛 郭立新[1] 杨海涛[1] 夏兴兰[1] Shi Dongxiao;Zhou Zhen;Guo Lixin;Yang Haitao;Xia Xinglan(FAW Wuxi Fuel Injection Equipment Research Institute,Wuxi 214063,China)

机构地区：[1]中国一汽无锡油泵油嘴研究所,江苏无锡214063

出　　处：《内燃机学报》2019年第1期54-59,共6页Transactions of Csice

摘　　要：柴油机喷油嘴内部空穴流动很大程度上影响燃油雾化,进而影响整机排放.在比例放大透明油嘴内部空穴流动可视化试验台上,通过高速摄影和长工作距离显微成像技术,研究了不同喷射压力、针阀升程和喷孔结构对空穴流动的影响.试验观察到两类空穴现象,一类是由几何结构诱导的膜状空穴,另一类是由涡流中心低压诱导的线空穴.研究表明:提高喷射压力、增大针阀升程有利于膜状空穴发展,渐缩形喷孔则会抑制膜状空穴发展.线空穴与流场中涡流密切相关,随着喷射压力的提高,线空穴强度范围会增加.膜状空穴与线空穴均能增大喷雾锥角.Cavitating flow in diesel injector nozzles affects the atomization behavior,which then strongly affects performances and emissions of diesel engine.Experiments were carried out to study the cavitating flow under different injection pressures,needle lifts and nozzle structures based on a visualization system with transparent scaled-up injector nozzles.A high speed CCD camera equipped with a long distance microscope device was used to capture the cavitation and spray images.The results show that two kinds of cavitation phenomenon are observed:one is film-type cavitation induced by nozzle geometrical structure,and the other is string cavitation generated in the low pressure region at the center of vortex flow.Moreover,the increase of injection pressure or needle lift will contribute to the development of film-type cavitation,while tapered nozzle will suppress it.It is also found that the string cavitation is closely related to the vortex flow in the nozzle,and the strength of string cavitation increases with the increase of injection pressure.In addition,both the film-type cavitation and string cavitation will increase the spray cone angle.

关 键 词：柴油机 喷油嘴 可视化 空穴流动 线空穴 喷雾 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]