Numerical simulation of fuel flow in an automobile fuel supplier. (3rd Report, Analysis of transient flow in an intake manifold).

Dynamic characteristics of fuel flow in an intake manifold of an automobile fuel supplier are analyzed by a three-dimensional computer program for a gas-liquid two-phase flow. The mechanism of the air-fuel ratio increase is clarified for the cases where the throttle valve opening varies from 20 degrees to wide open throttle (WOT). when the throttle valve is choked, air velocity is large not only at the throttle valve but also in the whole intake manifold and fuel is transported to an engine cylinder by this high velocity air. On the other hand, air velocity decreases when the throttle valve is opened, and fuel is slowly transported to the engine cylinder and some portion of injected fuel remains in the intake manifold after the suction stroke. Therefore the fuel amount which flows into the cylinder decreases just after opening the throttle valve.