激光诊断及数值仿真在柴油机V形交叉孔油嘴研究上的应用

Application of Laser Diagnosis and Numerical Simulation in Study on V-Type Intersecting Hole Nozzle for Diesel Engine

提出一种应用于柴油机的V形交叉孔油嘴结构,可视化结果表明了从交叉孔油嘴喷出的喷雾具有明显的扇状结构特征。试验比较了一个单孔油嘴和2种具有不同交叉角的交叉孔油嘴在不同试验条件下的喷雾特征,其中包括喷雾角及贯穿距。从雾化的角度比较分析采用PDA获得的3种试验油嘴的粒子算数平均直径(D10)的大小。采用喷雾体积放大倍率的概念定性地分析了油嘴结构及边界条件对喷雾分布及雾化特性的影响,与单孔油嘴相比,交叉孔油嘴具有更小的粒径及更高的喷雾体积放大倍率。喷孔内流的三维仿真计算表明:交叉孔结构对喷孔内流的影响是形成扇状喷雾及较大喷雾角的主要原因。

A new-type nozzle named V-type intersecting hole nozzle（IH nozzle） was proposed for diesel engine. According to the results observed with visualization technology, the spray injected through the V-type IH nozzle was of fan-shaped formation. Its spray characteristics, including spray angle, penetration and atomization of two IH nozzles with different intersecting angles were studied and compared with a single hole nozzle（SH nozzle） under variable boundary conditions. The fuel droplet mean diamenters （D10） for the three nozzles were measured by using Phase Doppler Anemometry. Meanwhile, the spray volume enhancement ratio was used to qualitatively analyze influences of nozzle structure and boundary conditions on spray distribution and atomization. The results show that the fan-shaped spray of IH nozzle has smaller droplet diameter and higher spray volume enhancement ratio compared to the conical spray of SH nozzle. Three-dimensional simulation shows that influence of intersecting hole structure on in-nozzle flow is the primary reason to form fan-shaped and large angle spray.