The Interaction of Air Motion, Fuel Spray, and Combustion in the Diesel Combustion Process

Abstract

This paper is pertinent mainly to combustion in open-chamber diesel engines employing air swirl. It is shown how an increase in air swirl rate can cause a marked loss of combustion efficiency unless fuel spray penetration is increased. High swirl reduces radial fuel spray penetration with central injection and the resulting excess fuel in the central area may be trapped by buoyancy forces following ignition, becoming isolated for as much as a tenth of a second in a chamber of four in. diameter. A brief explanation of fuel injection in terms of the mechanics of fluid jets is given and circumstances described in which buoyancy forces assist fuel-air mixing following ignition.