非对称多孔喷油器撞壁喷雾特性的试验与模拟

采用高速阴影摄像技术对直喷汽油机非对称多孔喷油器进行了撞壁喷雾特性研究.分析了撞壁距离和撞壁角度对撞壁喷雾贯穿距和半径的影响.利用计算流体力学CFD(Computational Fluid Dynamics)技术研究了撞壁距离与撞壁角度对撞壁喷雾粒径SMD(Sauter Mean Diameter)、壁面油膜厚度以及壁面油膜面积的影响.结果表明,撞壁距离与撞壁角度对撞壁喷雾有着重要影响,在试验条件下较佳的撞壁距离大约为26.1,mm,即压缩/进气上止点前后60°CA左右,较合适的撞壁角度应该是75°左右.此外,喷雾离开喷嘴3,ms后,撞壁距离为26.1,mm时,撞壁喷雾粒径SMD平均较撞壁距离18.1,mm时大了约1,μm,而比撞壁距离47.1,mm时小了约14,μm;撞壁角度为75°时,撞壁喷雾粒径SMD平均较撞壁角度60°时小了约5,μm,而比撞壁角度90°时大了约1.6,μm.

Experiment and Simulation on Impinging Spray Characteristics of an Asymmetrical Multi-Hole Injector

Impinging spray characteristics were investigated based on asymmetric multi-hole injector of direct injection(DI)gasoline engines using high-speed shadow photography.Effects of impinging distance and impinging angle on impinging spray penetration and radius were analyzed.Effects of impinging distance and impinging angle on SMD,wall film thickness and wall film area were also studied by means of CFD technique.Results show that,impinging distance and impinging angle have an important influence on the impinging spray development.For the injector and the piston in the experiment,the proper impinging distance is about 26.1,mm(60,°CA before and after top dead center of compression and intake stroke);the proper impinging angle is about 75°.In addition,after 3 ms of injection starting,the SMD under impinging distance 26.1,mm is averagely larger than 1 μm and less than 14,μm compared with the ones under impinging distance 18.1,mm and 47.1,mm respectively;the SMD under impinging angle 75° is averagely about less than 5,μm and larger than 1.6,μm compared with the ones under impinging angle 60° and 90°.