Abstract
The stratified air-fuel mixture formation for stratified SI (spark ignition) combustion, and the homogeneous air-fuel mixture formation for both homogeneous SI combustion and HCCI (homogeneous charge compression ignition) combustion, in a direct-injection gasoline engine, have been three-dimensionally analyzed by means of the authors' GTT code with a fan spray model which was validated by the authors' group. The effects of various in-cylinder gas flows on mixture formation, by means of a fan spray, have been investigated by using intake valves with shrouds in various layouts. Furthermore, the effects of the fuel injection direction and the injection timing on mixture formation, have also been investigated. As a result, it has been found that both stratified mixture and homogeneous mixture can be formed stably at a wide range of engine speeds by only changing the fuel injection timing, with the fuel injection direction in accordance with the in-cylinder gas flow direction.
