Three-dimensional Transient Numerical Study On The Flow Character In Cylinder Of Engine For Car

At present, the engine with higher efficiency and lower pollution is regarded as one of the major developing projects in many countries. The intake process is the key part to the working circle of the engine. The flow character in the intake process would affect the spreading velocity of the flame, the stability of the combustion and its combustion efficiency. In recent years, the topic has been extensively explored nationally and internationally. How to implement the three-dimensional transient numerical study on the flow character in cylinder of engine is the hot topic to all of researches. The transient numerical simulation method approaches the real process and the messages of the flow fields of the cylinder in the process of the engine can be obtained directly, checking the design of the intake system is fitful or not, and the structure of the intake system can be changed on accounts of the need of the engine in order to obtain reasonable the flow fields.Dynamic mesh technique is the key of the transient numerical simulation to the intake process of the engine, and the Combined Dynamic Mesh Technique (CDMT) is presented based on Finite Volume Method (FVM) in this paper. Based on CDMT, the problem that involves many sliding sides about the study object is solved. The intake process of 1.9TDI engine produced by DaZhongBaoLai Company is studied with Three-dimensional transient numerical method in this paper. The intake process transient character of the engine is simulated with different shape intake, different rotate speed and different compressing ratio, and the same time, the intake process transient character is also investigated with single intake and two intakes. In the end, the mass flow coefficient and volumetric efficiency are analyzed, and turbulent intensity, pressure and velocity fields of engine in the intake process are also discussed in this paper.The investigated results show that the shape and the position of intake port have an insignificant influence on flow field such as velocity distribution, pressure and turbulent intensity in engine at the initial stage. The flow field changes with moving piston during the intake process, thus it makes the flow be changed quite complicated, as a result, the flow in the engine is not swirl or tumble flow, and it is the combination of these two during the intake process. The volumetric efficiency of the engine system and the turbulent intensity restrict each other. The rotate speed of engine is direct ratio with the...