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
Based on schlieren imaging method the shock wave generated by diesel injector has been investigated,and the influences of ambient gas property, the progress of the spray, ambient gas density and ambient gas temperature on shock wave have been analyzed. The results show that:the images of spray shock wave are cleaner using sulfur hexafluoride(SF6) as ambient gas than using the nitrogen(N2); at the beginning of injection, shock wave phenomenon does not generate immediately as the fuel leave the nozzle because of the needle movement, and the hesitation is decided by the injection condition and characteristics of injector. The generation of shock wave in the spray tip and the detachment of shock wave from the spray tip show little effect on the spray macroscopic characteristics. The ambient gas density and temperature have a significant effect on the maximum of spray tip velocity, types of shock wave and the detachment timing of shock wave from the spray tip.
