Geometric optimization of Nozzles for Inclined Injectors for DI Diesel Engines

Low emission heavy-duty diesel engines are increasingly utilizing four-valve designs with vertical central injectors. However, two-valve DI diesel engines with inclined injectors offset from the centerline of the piston bowl are likely to continue to be used in medium and light duty applications for some time. In such situations, designing of the hole-type nozzle is very difficult and may cause unavoidable back-drilling problems. The purpose of this paper is to solve back-drilling problems connected with hole-type nozzles and improve fuel-air mixing which leads to more efficient combustion. Based on geometric considerations, this paper introduces single-cone hole-type nozzles, double-cone hole-type nozzles, and the critical principal angles for hole-type nozzles. The single-cone hole-type nozzles and double-cone hole-type nozzles can meet requirements for height of the spray impingement points and spray orifice distribution angle at the same time. The concept of the critical principal angle for hole-type nozzles provides a criterion for the determination of both the hole-type nozzle angles and the injector installation angle.

This paper also gives an example to illustrate the application of the above methods. Finally, this paper systematically summarizes design methods for hole-type nozzles that fit the DI combustion chamber.