The Numerical Simulation On Flow Field In Ports And Cylinder Of158FMI Gasoline Engine

The development of low emissions and low fuel consumption of gasoline productshas become an important direction in the development of today. The state of flowing airin the inlet-internal cylinder system of gasoline engine is very complexity，it has greatinfluence on mixture combustion speed, and then affect the performance of power,economy and emission. With the rapid development of computer technology, thenumerical simulation method has gained more and more attention, and it is widely usedto study the working process of the engine. Three dimensional simulation technologiesare used, based on computational fluid dynamics basic principles, numerical simulationof the inlet-cylinder gas flow process was studied on158FMI engine.The steady numerical simulation result shows that, tumbles and two symmetricalvortices in the opposite direction occurred evidently in the flow field of the cylinder，thestructure of the ports was appropriate. Maximum error between simulation and inlet porttest is in about8%, the average error is less than5%，Simulation and experimentalresults are in good agreement.Technique for generating moving meshes were employed to build computationalmeshes rapidly before velocity and turbulent kinetic energy fields were computed byinstantaneous simulation and also obtain more detailed information of flow field. Aftercomparing transient stimulation analysis results on the original model, it was found thatit could form large-scale inclined-axed whirl, in which the tumble played the main roleand kept until compressed TDC. The turbulence kinetic energy distribution of theoptimization model showed that crowded flow function of Concave head piston wasmore apparent， before the ignition relatively large turbo kinetic energy compared withflat head piston was kept, which were good to accelerate the flame core formation andimprove combustion stability and thermal efficiency is favorable.In this paper, steady state and transient simulation were used in the research offlow field in ports and cylinder of engine，which reveals the movement characteristicsof flow field in cylinder and the effect that combustion chamber structure on theevolution of the transient flow field, it also provides a theoretical guidance for theengine ports structure and combustion chamber design.