柴油机喷嘴内线空化对喷雾影响的试验  

Experiment on the Influence of String Cavitation on Spray Angle in Diesel Injector Nozzles

作　　者：孙申鑫 何志霞 冷先银 段炼 郭根苗 陈舟 Sun Shenxin;He Zhixia;Len Xianyin;Duan Lian;Guo Genmiao;Chen Zhou(School of Power and Engineering,Jiangsu University,Zhenjiang 212013,China;Institute for Energy Research,Jiangsu University,Zhenjiang 212013,China)

机构地区：[1]江苏大学能源与动力工程学院,江苏镇江212013 [2]江苏大学能源研究院,江苏镇江212013

出　　处：《内燃机学报》2019年第3期244-250,共7页Transactions of Csice

基　　金：国家自然科学基金资助项目(51776088);江苏省自然科学基金资助项目(BK201613490)

摘　　要：设计3种不同尺寸的锥度孔透明喷嘴,在尽可能抑制壁面空化的情况下研究了喷油压力、喷嘴孔尺寸及针阀升程对喷嘴内线空化的出现规律、强度及瞬态特性的影响,进而对喷雾的影响.结果表明:在喷嘴低针阀升程时会存在起源于针阀锥面处的线空化,可轻易延伸至喷孔出口,形态粗壮,引致非常大的喷雾锥角,而随针阀的抬起,这类线空化消失,代之以孔与孔之间的线空化,空化形态较细,对喷雾锥角影响相对很小,这为柴油机启喷阶段和喷油末期喷雾锥角的骤增与波动提供了一种合理解释;喷雾锥角的波动与线空化发展程度及其延伸至喷孔出口处的空化厚度间存在强烈的依存关系;线空化对喷雾的影响存在迟滞现象,这与空化泡喷出喷孔后破裂及流体运动惯性有关.Three different dimensions of the transparent nozzles with tapered orifices were designed in order to eliminate the occurrence of the normal cavitation. The influence of injection pressure,nozzle size and needle lift on the occurrence,intensity,transient changes of the string cavitation,and thus on the spray characteristics. It is found that thick and strong kind of string cavitation always occurs on the tapered needle valve surface when the needle lift is small,leading to a bigger spray angel. As the needle lifts up,the thick and strong kind of string cavitation disappears and is replaced by another slimmer kind of hole-to-hole string cavitation,which has a little influence on the spray angel. This provides a reasonable explanation for sudden increase and fluctuation of the spray angle during the beginning and the end of injection behavior. The research results also indicate that the spray angle has a strong relationship with the string cavitation development and the bubble thickness at the valve exit. A hysteresis phenomenon exists during the influence of the string cavitation on the spray atomization,which is related to the time of cavitation bubble fracturing outside and the inertia of fluid motion inside.

关 键 词：柴油机 线空化 锥度孔 喷雾锥角 涡旋运动 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]