Numerical Simulation Of Diesel Engine Fuel Injection Characteristics And Nozzle Transient Cavitation

In recent years,en ergy con servation and environmental protection have become a h ot spot in social research,and diesel engines,as an important part of industry power,are even more important research topics.The small size,high injection pressure,and fast diesel fuel flow of diesel engine injectors result in very complicated physical changes in the injection hole,making it difficult to study.Under normal circumstances,researchers use the principle of "geometric similarity" to establish an enlarged transparent experimental device for experiments or use numerical simulation to study the fuel injection process.On the basis of this hypothesis,many research results have been obtained.However,with the deepening of research,some researchers have found that only considering the diesel flow when the needle valve body is in a fixed position is limited.In reality,the movement of the needle valve body is composed of upward displacement-static-downward displacement.In this paper,the dynamic grid technology is used to realize the transient simulation of the diesel flow in the injection hole.At the same time,the variation characteristics of the cavitation phenomenon in the injection hole under different working conditions and geometric parameters are analyzed and compared.In this paper,the flow simulation of the fuel injection process of a certain injector is carried out,and the needle valve body displacement of the injector with time variation curve under different working conditions and geometric parameters is obtained;then the needle valve body displacement variation curve with time is obtained User-defined programming through C language;then establish a three-dimensional model of the injector fluid domain and perform mesh division;then use user-defined programs in Fluent to drive the mesh movement and perform grid independence and step size independence Performance verification;finally get the flow state and cavitation phenomenon of diesel oil in the injection hole under transient that this transient simulation method is closer to the injection process in which the needle valve body of the actual injector keeps moving.After clarifying the movement of the needle valve of the diesel injector,according to the proposed calculation model of the injector nozzle,the influence of the working condition parameters and structural parameters on the cavitation phenomenon in the injection hole is analyzed,and the conclusion is that it is most conducive to precise control.The structural parameters of the injector to inject fuel and improve the efficiency of diesel combustion.The research shows that a series of working conditions and structural optimizations carried out in this paper can improve the control accuracy of the injector and the diesel combustion efficiency,and the comparison and analysis of the experimental measurement results in reference documents verify the correctness of the model establishment and simulation.