Development Of Gasoline Engine Standard Model For Performance Simulation Based On Similarity Study Of Thermal Power Conversion Process

The engine numerical simulation technology is widely used in the modern engine development process,greatly shortens the cycle of engine design and development,and effectively improves the efficiency of engine performance optimization.At present,there are some problems in engine simulation technology: the process of modeling is tedious,the parameters need to be determined or optimized,and the workload is huge;the accuracy of the simulation model is difficult to guarantee,which mainly depends on the grasp of the boundary conditions;the guidance of the optimization direction is lack when the calculation results are different from the development targets.At the same time,under the background of energy crisis and energy saving and emission reduction,high efficiency and energy saving turbocharged direct injection gasoline engine has broad prospects.Therefore,this paper puts forward a standard simulation model for the pressurized direct injection gasoline engine based on the Similarity Study of the heat transfer process in the cylinder.The parameter transplantation is carried out between the different engines of same type,and the precise boundary conditions are provided for the performance simulation of the engine.And the direction of optimization guidance is provided for the engine performance numerical developmentIn this paper,by comparing the performance and structure of several advanced engines,the similarity of engine gas dynamics,combustion process,heat transfer process,and the similarity law in the process of heat transfer are summed up to solve the internal relationship between engine performance and design and operating parameters.Finally,the standard simulation platform of the turbocharging direct injection gasoline engine is established and verified.The results show that different intake and exhaust systems satisfying the similarity criterion of aerodynamics can obtain the same charge coefficient speed characteristic curve.There is a very good linear relationship between the combustion efficiency and the excess air coefficient in the thermal power conversion process in different engine cylinders.In the Webb combustion model,there is a quantitative function relationship between the combustion duration and the 50% burning position points respectively with the rotational speed,the ignition point,the excess air coefficient and the residual exhaust gas coefficient in the cylinder.And the combustion quality parameters will be around 2,and the combustion quality parameters will be less than 2 under the very small load,and there is a good linear relationship between the adiabatic efficiency and the excess air coefficient during the thermal power conversion process in the cylinder.With the aid of the above similarity law,the standard numerical model and performance simulation platform of the supercharged direct injection gasoline engine are set up.The important parameters of the 1.4T turbocharged direct injection gasoline engine are transplanted into the 1.5T engine model.The trend of torque and BSFC change with the speed is basically consistent with the target value.The engine parameters are different,and the simulation results are close to the target values of the engine after optimization.