Three-Dimensional Computations of Flow and Fuel Injection in an Engine Intake Port

Abstract

An existing multidimensional in-cylinder flow code, KIVA, was modified to calculate gas flow and fuel injection in a simplified (no valve stem and simplified valve-head geometry) engine intake port. A single-cylinder engine simulation program was used to specify the initial and boundary conditions for flow calculations. A previously developed spray model was also used to simulate pressure-atomized spray with isooctane as the fuel. Three cases with increasing degrees of complexity were considered: (1) an impulsively started port flow with both port ends open (the inlet-boundary velocity was changed from zero to a finite value at the start of computation), (2) an impulsively started port flow with one port end partially blocked to simulate gas flow through the valve annulus, and (3) port flow driven by the time-varying gas flow rate through the valve annulus calculated using a single-cylinder engine simulation program. A spray calculation was also made for each case. The calculations indicate that the KIVA code can be modified to conduct computations with complicated port geometries and open flow boundary conditions. The results also indicate that both gas flow and fuel-injection processes and port geometry have a strong influence on the details of fuel induction into the cylinder. This confirms that consideration of both gas flow and fuel-injection processes is necessary in order to understand the mechanisms of fuel-air mixing in an engine intake port employing port fuel injection.