Prediction of Effects of Intake Port and Chamber on Combustion Performance of Gasoline Engines

Abstract

Steady state flow tests of different tumble intake ports matched with different S/V (surface-to-volume ratio) combustion chambers have been carried out. The results show that the flow coefficient of a medium tumble port is decreased by 4 %, but the tumble ratio is increased by 28 % in comparison with a low tumble port. The combustion chamber has little influence on intake port steady flow performance. The combustion simulation of low tumble port matched with high S/V combustion chamber has been carried out firstly, which agrees well with the test results. Base on these models, in-cylinder combustion analysis of different tumble intake port matched with different S/V combustion chamber has been carried out at 2000 rpm & full load condition. The results show that with the same combustion chamber, turbulence kinetic energy (TKE) of medium tumble port is increased by 15 %, burn duration is decreased by 3 °CA, and the peak cylinder pressure is increased by 0.8 MPa in comparison with low tumble port. With the same intake port, TKE of the low S/V chamber is increased by 13 %, burn duration is decreased by 1 °CA, and peak pressure is increased by 0.5 MPa in comparison with the high S/V chamber. The HC and soot emissions is decreased obviously but NOx is increased to some extent. The comprehensive predications show that both intake port and combustion chamber influence combustion performance of the gasoline engine significantly. The intake port has more effect on combustion behavior compared with the chamber. It is helpful to improve combustion performance by increasing tumble ratio of intake port and/or decreasing S/V ratio of combustion chamber.