A contribution to the design of a novel direct- injection diesel engine combustion system— analysis of pip size

Abstract A novel design of direct-injection diesel engine combustion system is outlined. Preliminary calculations indicate that the system has the potential to adequately distribute the fuel spray over the piston bowl. The spray is distributed away from the bowl wall and thus provides the potential for good vaporization and mixing with air. This may be possible without resorting to swirling the flow. If so, substantial efficiency gains would be made over conventional highly swirled systems. An analysis of the size of the pip upon which the spray isimpacted has led to the identification of the optimum pip size. This is based on the Sauter mean diameter of the spray and the volume occupied by the spray. Comparisons made with one experiment indicate that the present impaction submodel deals well with the momentum and energy losses on impaction. However, subsequent spray motion is not well predicted in terms of the penetration rate. Areas for further research are identified.