Effect of nozzle geometry on combustion of a diesel-methanol dual-fuel direct injection engine

Abstract

A three-dimensional model of fuel combustion in a diesel-methanol dual-fuel direct injection engine is constructed to study the effect of nozzle geometry. The model includes two nozzles, one for diesel injection and one for methanol injection. Based on the geometric modeling and empirical formulas for the nozzle, the influence of fuel flow in the nozzle on fuel combustion in the cylinder is calculated. In the geometric modeling, the influences of the R/D and L/D parameters on the effective injection radius of the nozzle, the spray velocity at the outlet, and the fuel’s Sauter mean diameter in the cylinder are analyzed. For the flow simulation inside the nozzle using empirical formulas, the effects of discharge coefficient and spray angle are analyzed. The simulation results show that a larger R can increase engine power. Both R and L have an impact on the formation of pollutants. The discharge coefficient has a greater impact on the performance of the engine than the spray angle, and a suitable spray angle is around 13°. The effects of dual-fuel nozzles with different diameters on combustion temperature and pollutant emissions in the engine cylinder are analyzed through experiments.