Application And Validation For Quasi-dimensional Combustion Model Of Turbo-charged Diesel Engine

The research of combustion process is the basis of the performance study of diesel engine working in plateau area. The quasi-dimensional combustion model can predict the combustion process and it has a short computing time. Thus it is suitable to be used to study the combustion characteristics of diesel engine in steady and transient operations. But before it is used, it needs to be validated.In order to provide experiment data for the validation, the plateau experiment was launched and the data of combustion and performance were collected of a turbo-charged diesel engine working in 0m, 2000 m, 3000 m, 4000 m and 4500 m. At the same time, the simulation model was built and verified in GT-Power simulation platform.In order to study the validation method of the quasi-dimensional combustion model, the theory of a two-zone quasi-dimensional combustion model was analyzed. The effects of the four parameters in the two-zone quasi-dimensional combustion model on the combustion were conducted.Then the method of DOE combined with Genetic Algorithm was raised and the validation was done. At last, the optimium group of parameters were got and verified.The two-zone quasi-dimensional combustion model was applied in the simulation model of the turbo-charged diesel engine. The prediction ablity of the model in different altitude were verified firstly. Then the combustion characteristics of the engine in steady and transient operations were studied. The results show that, in steady operations, with the increase of the altitude, the intake pressure decreases, the ignition delay increases, CA50 comes earlier and the combustion duration becomes short. In the constant speed and increasing torque transient operations, the increase of the intake mass fall behind the increase of the fuel mass, caused by the slow response of the turbo-charger. Thus the air fuel ratio in the transient operation drops, CA50 comes later, the combustion duration becomes longer and the combustion deteriorates. And this phenomenon becomes more serious when the altitude increases.