Research On Fluid-Solid Coupling Simulation Of The Diesel Engine Spray Nozzle

This paper focus on the studies of the gas flow back characteristics and temperature distribution in the nozzle at the end of the fuel injection based on the diesel engine nozzle flow and deposit formation in circumstance of existing research results to analysis the cause of the deposit inside the nozzle. As the interval of the diesel fuel injection shorter and the growing popularity of the injection technology for many times, it is a significant research project, and it is necessary to carry out for further research. It is difficult to obtain the nozzle inside and outside the actual working cycle thermodynamic parameters with the experimental methods at present. Therefore, the CFD method was adopted to recycle to the working process of diesel engine to study the flow and temperature distribution inside the nozzle in this paper.The diesel engine BOOST construction of one-dimensional performance model was built after the rated performance correction model. The transient pressure and temperature of inlet and exhaust port boundary conditions and other related parameters were calculated for CFD numerical simulation. And it is the foundation of the fluid-solid coupling numerical simulation of the nozzle.A variety of software was used to carry out the work at geometry file construction and the conversion of format in the diesel engine. This paper focus on the modeling process and the file conversion process before the CFD program imported. It discusses the superiority and necessity of file conversion process. In this paper, the means of processing was proposed through the surface modeling, model file format conversion, and repairing by imported CFD geometry program by step. The CFD calculation efficiency can be improved in the early period of the complex model. The model parameters of turbulence, spray, ignition and combustion were set, and the output rules formulated the calculation results were made out aimed at setting different regional boundary and initial conditions with the CFD software.The analysis of nozzle deposit formation was carried out based on the cylinder flow field in the diesel engine working cycle. The numerical simulation research at rated output rotational speed was carried out in cylinder flow field of the whole working cycle. And it analyzed the cyclical fluctuation characteristics of thermodynamic parameters in the flow field of the cylinder, and emphatically analyzed the thermodynamics impact of transient high temperature and high pressure of the gas flow field around the nozzle flow and pressure indoor area. Then the analysis on deposit formation was carried out due to the nozzle jet gas flow back shock produced by high temperature.This paper developed the fluid-solid coupling simulation at the cylinder nozzle tip based on the CFD software super-cycle coupling technology. According to the periodic characteristics of internal combustion engine, it developed numerical simulation of the nozzle cycle related coupling system transient heat transfer. And the maximum torque was calculated under the condition of a different time working cycle in the coupled system of temperature field. This paper analyzed the gas heating effect to the nozzle in the whole working cycle in the cylinder. At the same time, according to the temperature distribution inside the nozzle of solid in the working cycle, it analyzed the cause of deposit formation inside and outside the nozzle.