NUMERICAL ANALYSIS OF FUEL FLOW PATTERNS AT THE NOZZLE EXIT CONSIDERING DIFFERENT FUELS AND OPERATING PARAMETERS OF A DIESEL ENGINE

The paper presents a numerical study (Eulerian multiphase approach) on the influence of physical characteristics of different fuels (density and dynamic viscosity) on the fuel flow pattern at the injection nozzle exit considering different fuels and operating parameters of a diesel engine (fuel temperature and compression ratio). A new term, Nozzle Uniformity Coefficient (NUC) was introduced to define the fluid flow pattern at the injection nozzle exit and to correlate its value with a further development of the spray in the combustion chamber. The results of the analysis show that the structure of the fluid flow pattern is the most homogeneous in the case of low fuel temperatures and low back pressures. Fuel velocities have an immediate effect on the spray development, the air-fuel mixing process, and the depth of jet penetration into the combustion chamber. The average values of biodiesel fuel velocities are lower compared to those of diesel fuel. In view of the increasing use of fuels from renewable sources (biofuels), a logical conclusion is that it is necessary to correlate the injection system components with their physicochemical properties.