Simulation And Research On The Car Engine Air Intake System With CFD

The gas flow within the engine intake system is very complex and transient, which distribution is uneven. The folw field of the gas determined the performance of engine. Only we are familiar with the folw field of the gas, can we design a more reasonable structure of air intake system. Through the above measures, it not only improves the charging efficiency and changes the gas flow in cylinder,but also increases the turbulence intensity of gas at the end of the compression process in the intake process. So it can improve the flame propagation efficiency and increase fuel burning completeness. Thus it can improve the engine performance and reduce exhaust pollution emissions.It is difficult to measure the gas flow situation in the intake system by the experiment. It not only can obtain a lot of information of the gas flow through the simulation, but also can greatly curtail the experimental cycle through CFD numerical simulation. Therefore, it is an important method to study the gas flow in the engine intake system. This paper has researched on the effect of pressure, velocity and turbulent kinetic energy of the engine air intake system using FLUENT simulation software.This paper bases on a certain type of engine as research object. It哈has established the three-dimensional physical model of air intake system by UG. We simplify the 3D model on condition that it would not affect the accuracy. The meshes and boundary conditions of the physical model set by GAMBIT which is pretreatment software of FLUENT. We make sure the flow of air inlet through the simulator and establish the flow equation by GAMBIT also. After simulation completed, we get the result of the flow distribution of pressure, velocity and turbulent kinetic energy inside the air intake system. The analysis shows that the design of the type engine's air intake system is reasonable, as the intake of air cylinder is relatively full. But there is any pressure in cylinder is slightly lower at the end of air intake and the gas is uneven. So it fail to form the tumble movement. At the end of compression, the formation of turbulent intension is not strong enough to increase the flame propagation efficiency. Therefore, we put forward three ways such as changing the airway curvature, changing the pistons tilt angle and changing the bottom bending degree. So we establish a new model to simulate and compare it with the prior. The second result shows that pressure at the end of the air intake in cylinder has increased, the tumble movement has formed, and the compression process flow turbulence intensity has increased. These ways not only improve the engine intake rate, but also the inside cylinder gas combust. Further more, it increases the engine performance and reduces the exhaust emissions of pollutants. This paper can provide an important theoretical guidance at the field of the engine air intake system.