喷射压力对喷孔流量及内部空化的影响  

Influence of inlet pressure on flow rate and internal cavitation of nozzle

作　　者：雷艳[1] 高壮 仇滔[1,2] 宋鑫 LEI Yan;GAO Zhuang;QIU Tao;SONG Xin(College of Environment and Energy Engineering,Beijing University of Technology,Beijing 100124, China;Beijing CollaborativeInnovation Center of Electric Vehicles,Beijing 100081, China)

机构地区：[1]北京工业大学环境与能源工程学院,北京100124 [2]北京电动车辆协同创新中心,北京100081

出　　处：《哈尔滨工程大学学报》2018年第5期949-954,共6页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(51006012);北京市教育委员会科学与技术发展项目(KM201610005018;KM201310005033)

摘　　要：流量特性是评价喷油器性能的主要参数,为探究喷射压力对流量特性的影响规律,本文采用比例放大单孔喷油器,结合试验与三维仿真,分析了随入口压力变化,喷孔内空化流动规律以及该空化流动对喷孔燃油流量特性的影响。研究结果表明:出口背压不变,随入口压力升高,喷嘴入口处出现空化并向出口发展,入口截面处空化面积达到最大后不再变化,燃油质量流率不断增加。燃油流量系数(Cd)变化分为三个阶段:P_(in)<0.8 MPa,C_d为常数且只与喷孔的结构有关;0.8 MPa<P_(in)<1.8 MPa,C_d急剧下降且与入口截面的收缩系数及空化数有关;P_(in)>1.8MPa,C_d与空化数有关,喷射压力越高,空化数越趋近1,C_d也越趋于稳定。Flow is an important parameter in the evaluation of injector performance. To investigate the effect of injection pressure on discharge,along with performing a computational fluid dynamics（ CFD） three-dimensional simulation,we built a scale-hole injector nozzle to investigate the effect of the inlet pressure of a diesel nozzle on flow. We analyzed the variation law of cavitation flow inside the nozzle with changes in inlet pressure and the effect of cavitation flow on the flow of fuel oil inside the nozzle. The results show that,as the outlet backpressure remains constant with increases in inlet pressure,cavitation occurs at the nozzle entrance and develops toward the outlet. When the cavitation area at the inlet section reaches its maximum value,it holds constant and the fuel mass flow rate steadily increases. The development process of the discharge coefficient（ Cd） can be divided into three stages： at P（in）0. 8 MPa,Cdis constant and related only to the nozzle structure; at 0. 8 MPaP（in）1. 8 MPa,Cd sharply decreases and is related only to the shrinkage coefficient and cavitation number in the inlet section; at P（in）1. 8 MPa,Cd is related to the cavitation number; as the inlet pressure continues to increase,the cavitation number approaches 1 and Cd tends to become increasingly stable.

关 键 词：柴油机 喷孔 入口压力 空化 流量特性 等效压力 比例放大 计算流体力学 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]