Applying a Diesel Spray Model With Different Size Distribution Functions to High Pressure Diesel Spray Cases

Abstract

In diesel engine sprays, smaller sized droplets aid the combustion process, thus reducing emissions. Thus, it is important for diesel engine spray models to satisfactorily represent hydrodynamic mechanisms. A further development of a diesel spray model that uses different size distribution functions has been presented. In this model transport equations are constructed to calculate three moments of the droplet size distribution, a fourth moment is calculated from a gamma size distribution function, while the results of the droplet break up process are derived from an assumed size distribution function. Together these present the complete hydrodynamics characterisation of the diesel spray. The motivation for using different size distributions is to reduce the complexity of the spray modelling process and reduce the computational expense. The model has been applied to high-pressure diesel spray cases with the experimental data characterised by diesel spray penetration at different injection pressure values. The results from the model indicate that diesel spray penetration is over predicted at the start of injection but this improves as the fuel injection progresses.