Optimization Development Of The Port And Combustion Chamber Shape Of A Turbocharged Gasoline Engine

As an important part of the working cycle of the gasoline engine, the combustion process plays a vital role of the performance, fuel economy and emission. It is necessary for developing the high performance and low emission engine to improve the efficiency of combustion and optimize the combustion process. The design of combustion system directly determines the volumetric efficiency of engine, the air flow and combustion in the chamber. The author intends to develop a type of 1.8T turbocharged gasoline engine by optimizing the design of the combustion chamber shape and ports structure with the simulation and experimental methods and making a deep research and analysis of the factors which influence the mixture flow and combustion performance.The author selects the suitable turbulent model, the combustion heat release model and the heat dissipation model, gives out the control equation discretization method and solving method, offer the determination method of boundary conditions, uses the commercial software CSI CONVERGE to establish a three-dimensional CFD numerical simulation model of gasoline engine. Then the author uses the simulation model to research the influence of combustion chamber shape and ports structure on the combustion performance and makes an optimal design of combustion chamber shape and ports structure. The author manufactures a testing engine, then the author do some development tests on the testing engine, the result turns out to meet the development goal, Here is the main conclusions: The throat structure is the main parameter which influence the tumble ratio of the ports, it is a useful way to change the throat diameter and structure to increase the tumble ratio. The velocity of the combustion can be increased when the compression ratio increased, but the risk of knocking rising too. The structure of piston has impacts on the air flow in the combustion chamber, the combustion velocity is higher when using the bowl piston than using the flat piston. Using the bowl piston and the compression ratio as 10.0,the result turns out to meet the development goal.