Three-Dimensional Numerical Analysis of Mixture Formation Process in the Cylinder of a Spark-Ignition Engine.

Abstract

A three-dimensional numerical analysis was applied to the prediction of the fuel vapor concentration profile in the cylinder of a typical four -cycle reciprocating spark ignition engine with an off center valve. The conservation equations of mass, momentum and energy were solved on the basis of the finite volume method. The ordinary two-equation model was employed as the turbulence model. It was assumed that the fuel injected in the intake port flows into the cylinder as a vapor. Calculation was done from the TDC of the intake stroke to the TDC of the compression stroke every 10 degrees of the crank angle. The temporal variations of velocity and fuel mass fraction profiles were predicted during both intake and compression strokes. The results showed that the fuel mass fraction distribution was not uniform at the last stage of the compression stroke. The effect of the inflow velocity distribution on the mixture formation process was discussed.