Search Results

The need to evaluate other fuel types for use in internal combustion engines has increased with the concerns related to the limited availability of fossil fuels and the need to reduce emissions. In this assessment, two alternative-to-diesel fuels, dimethyl ether and biodiesel, are characterized by their spray tip penetration at different axial distances from the nozzle tip and at different ambient pressure values. The sauter mean diameter values at various axial distances from the injector tip are also evaluated. A novel diesel spray model that presents the hydrodynamics features of sprays from the moments derived from a Gamma size distribution and the droplet-size distribution function, rather than from droplet-size classes, is used for the numerical predictions. The results indicate that the spray tip penetration for both fuels increases rapidly initially but the rate of increase slows at the later stages of the fuel injection.

Creating small sized droplets is the primary reason for using sprays. In high-pressure diesel engine sprays, smaller sized droplets aid the combustion process, thus reducing emissions. Therefore, the adequate representation of the droplet breakup process in diesel engine spray models is essential. Two droplet breakup models have been applied in this study. These models have been developed based on whether the results of the droplet breakup processes have been derived from approximations, using an assumed size distribution function, or based on empirical data, using a gamma size distribution function. The effects of assumptions in the models, such as the number of sibling droplets produced during the breakup process, are also presented.