| In response to the global shortage of oil resources and stringent greenhouse gas emission control regulations,improve energy efficiency and reduce emissions has become the focus of diesel engine development direction.As the final component of the fuel injection system of diesel engine,the nozzle has great influence on the penetration distance,fuel atomization and oil-gas mixing quality.The fuel state of injection hole is closely related to the quality of fuel atomization in the cylinder,which determines the economy,power and emission level of the diesel engine.In recent years,the perforation structure has become the research focus in the field of scientific research,especially with the technology of EDM and the development of laser drilling technology,the technology and the time of processing complex hole type are ripe.Therefore,it is necessary to analyze the nozzle orifice structure of diesel engine,to study the flow state of fuel and the atomization characteristics of fuel jet in depth.In order to improve the injection performance of the injector of 16V280ZJ diesel engine,an improved method for the nozzle structure is proposed,which is to improve the jet flow rate and improve the atomization quality of fuel in the unit time.The numerical simulation method is used to calculate the three-dimensional model of the nozzle flow field,and the results show that the outlet flow of the scaling nozzle is larger than that of the traditional direct-type nozzle,and the export has more gas phase fuel ratio,which is favorable for the initial atomization of the fuel injection.The research method of this paper is CFD(computation Fluid Dynamic).By using fluent software to calculate three-dimensional flow field model in the jet hole,a mixed multiphase flow model and a cavitation model are used to study the basic characteristics of the flow field in the jet hole,and the cavitation phenomenon can affect the effective flow area in the jet hole.By studying the influence of the outlet pressure on the flow fieldIt is found that the hole phenomenon with high intensity at the entrance corner of the nozzle will reduce the outlet flow.On this basis,the factors that affect the flow field in the scaling nozzle are also studied by defining the geometrical parameters of the two kinds of scaling holes.The results show that the proportional distribution of the tapered and tapered nozzle will affect the flow field in the spout hole.The outlet flow increases with the increase of the proportion of the tapered section in a certain range,and the expansion ratio of the scaling nozzle section can also affect the flow field in the nozzle,and the outlet flow increases with the expansion of the hole section in a certain range,But after a certain range of export flow will not increase the decline.This paper has made a basic research on optimizing the nozzle structure and parameters of diesel engine,and the factors affecting the flow performance of the oil are analyzed qualitatively,which is helpful for understanding the flow field regularity and designing the nozzle structure of the nozzle. |
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