3-Dimentional Numerical Transient Simulation and Research on Flow Distribution Unevenness in Intake Manifold for a Turbocharged Diesel Engine

The design of engine intake system affects the intake uniformity of each cylinder of the engine, which in turn has an important impact on the engine performance, the uniform distribution of EGR exhaust gas and the combustion process of each cylinder. In this paper, the constant-pressure supercharged diesel engine intake pipe is used as the research model to study the intake air flow unevenness of the intake pipe of the supercharged diesel engine. The pressure boundary condition at the outlet of each intake manifold is set as the dynamic pressure change condition. The three-dimensional numerical simulation of the transient flow process in the intake manifold of diesel engine is simulated and analyzed by using numerical method, and the change of the Intake air flow field in the intake manifold under different working conditions during the intake overlapping period is discussed. The dynamic effects of diesel engine intake boost pressure, rotated speed, and intake pipe geometrical characteristic on the air mass flow at the outlet of each intake manifold, intake air distribution quality, and maximum intake unevenness are analyzed. According to numerical calculation result, it was obtained that the main reasons affecting the intake unevenness of each cylinder of diesel engine and the methods to reduce the intake unevenness: The lower the intake boost pressure of diesel engine, the greater the maximum intake unevenness. The greater the intake overlapping angle, the greater the maximum intake unevenness. When the diesel engine was working at low rotated speed, the maximum intake unevenness was higher than that at high rotated speed due to the long intake overlapping time. By increasing the boost pressure of the intake air, the unevenness intake air distribution of the diesel engine during the intake process could be reduced.