Based on the high flux synchrotron X-ray of the Shanghai Synchrotron Radiation Facility (SSRF), high precision 3D digital models of diesel nozzle tips have been established by X-ray micro-tomography technology, which reveal the internal surfaces and structures of orifices. To analyze the machining precision and characteristics of orifice processing methods, an ap- proach is presented based on the parameters of the internal structures of nozzle orifices, including the nozzle diameter, the orifice inner surface waviness, the eccentricity distance and the angle between orifices. Using this approach, two kinds of nozzle orifice processing methods, computerized numerical control drilling and electric discharge machining, have been studied and compared. The results show that this approach enables a simple, direct, and comprehensive contrastive analysis of nozzle orifice processing methods. When processing a single orifice, the electric discharge machining method has obvious advantages. However, when there are multiple orifices, the error levels of the two methods are similar in relation to the symmetry of distribution of the orifices.
Zhi-jun WU Zhi-long LI Wei-di HUANG Hui-feng GONG Ya GAO Jun DENG Zong-jie HU
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.
The controllable active thermo-atmosphere combustor(CATAC) has become a utilizable and effective facility because it benefits the optical diagnostics and modeling. This paper presents the modeling research of the auto-ignition and flames of the H2/N2(H2/CH4/N2,or H2/H2O2/N2) mixture on a CATAC,and shows curves varying with temperatures of auto-ignition delay,the height of the site of auto-ignition of lifted flames,and flame lift-off height. The results of auto-ignition delay and the lift-off height are compared the experimental results to validate the model. A turning point can be seen on each curve,identified with criterion temperature. It can be concluded that when the co-flow temperature is higher than the criterion temperature,the auto-ignition and lifted flame of the mixture are not stable. Conversely,below the criterion temperature,the mixture will auto-ignite in a stable fashion. Stabilization mechanisms of auto-ignition and lifted flames are analyzed in terms of the criterion temperature.
