The Simulation And Optimization For Induction And Exhaust System Of Engine By Cfd

Due to the light weight, low noise, and good starting performance, gasoline engine has been widely used in family cars. However the energy shortage and environment pollution has been becoming seriously, the fuel efficiency and reducing emissions are the objects pursued by researchers. Intake system is an important part of the engine,it will not only seriously affect the engine's power performance, fuel economy, but also affect its exhaust emissions, vibration and the reliability. To improve the property of combustion and reduce pollution, research of air motion inside the system is necessary.As the restriction of the equipment in common use,the study on performance of intake system process only by experiment is not only long term, but also expensive. With the development of computer, numerical simulation plays is playing an increasingly important role, it has less capital investment, design and calculation speed, completeness of the information, the advantages of simulation capability. The numerical simulation is based on fluid dynamics and computational fluid dynamics. We set up a set of basic conserved equations in diversified complex conditions, then solve these simultaneous non-linearity partial-differential equations, and get the distribution of every variable in the whole flow field.In this paper, the situations of airflow inside gasoline engine were studied by numerical simulation. First, use three-dimensional equipment measured the engine's shape, then use three-dimensional modeling software UG required to establish the geometric simulation model, divide the model by the unstructured grid. Secondly, analysis a large number of reference and determine the RNGκ?εturbulence model, finite volume method. Based on numerical methods, the pressure field, velocity field, and turbulent kinetic energy field were shown. The calculation results shows:1, The intake valve is not located in the center line of the vertical cylinder, during the intake process, air flows unevenly and the intake valve played a spoiler role, below the intake valve of the air is around air entrainment, and produced a vortex.2, Analysis the velocity vector cross the section when the different crank angle, it shows swirl generated by the cylinder is the top-down development, gradually disappeared near Detroit office.3, Through the analysis of the intake system, improved the scheme, and the numerical simulation. Found that improved the structure conform to the concave top piston gas flow trends in the intake air when the loss was small, whether it is the pressure, velocity, or the end of the turbulent kinetic energy field, and the results were slightly better in improving the former. The conclusions of this paper lay a good foundation for future analysis and structure optimization, but also provide a certain reference for the improvement of experiments.