A two dimensional model for spray formation and evaporation in a HSDI diesel engine

Compression ignited diesel engines have been widely used in heavy-duty vehicles and are increasingly been used in light duty vehicles. In diesel engines power is generated by injecting the high pressure fuel into the compressed air in the cylinder near top dead center (TDC). For design considerations and engine out emissions prospective it is important to determine the effect of different operating parameters on spray penetration, evaporation and wall impingement.;A two dimensional model was developed to understand the physical processes encountered by the liquid fuel when it is injected into a high pressure and high temperature environment in a diesel engine by decoupling it from the chemical process. The model was also used to understand the differences in the rate of evaporation at different injection pressures. Effort was also made to model the real properties of gases and liquids during the evaporation process which is an important aspect, often neglected in many studies.;The results indicate that the vaporization rate increases with an increase in the injection pressure from 600 bar to 1200 bar at 1500 rpm and 3 bar IMEP. The temperature rise experienced by the droplets during vaporization is more uniform at the higher injection pressures. The time required for the bulk of the fuel to reach its critical temperature is lower at the higher injection pressures. Also the amount of fuel impingement on the combustion chamber wall increases with an increase in the injection pressure and fuel viscosity.