Air Motion and Combustion in a Swirl Chamber Type Diesel Engine

According to the previous investigation on a swirl chamber type diesel engine, an earlier outflow of the fuel into the cylinder brings about favorable combustion. However, there appears a flameless region in the midst of the swirl chamber when the injection nozzle is so directed as to ensure the outflow action. In this paper, a better utilization of the air of this flameless area was aimed by controlling the air motion. Through comparison of engine performance together with observations of flow pattern and flame development, the following results were obtained : In the presence of a strong air swirl, the combustion is retarded owing to a poor mixture formation. A rather weakened swirl, which is realized by a proper selection of direction of the connecting passage or by slightly obstructing the stream, causes a better fuel distribution which assists the flaming in the central part of the chamber, thus resulting in an improvement in the engine performance.