STUDY OF SPRAY CHARACTERISTICS OF BIODIESEL USING DIMENSIONLESS ANALYSIS UNDER NON EVAPORATING CONDITIONS

The spray characteristics of the fuel greatly influence emissions from diesel engines. Spray development plays a vital role in improving the combustion and emission characteristics of fuel because it directly affects the air- fuel mixture formation. The spray characteristics of fuel mainly depend on fuel injection process, fuel density, fuel viscosity, ambient pressure and temperature. Among these, the effect of fuel injection pressure is a very important parameter directly affecting spray structure. This study investigates the effects of fuel injection pressure on the spray characteristics such as spray angle and spray tip penetration in a constant volume chamber under non evaporating conditions by image processing techniques. The macroscopic spray characteristics were quantified using dimensionless analysis by examining the role of the dominating forces associated with liquid jet breakup. The Weber number, Reynolds number and air- to- fluid density ratio were used to capture the primary forces including the inertia, surface tension and aerodynamics drag forces. The Weber number has a more profound effect on the spray penetration and spray cone angle compared to the Reynolds number contribution. This analysis yielded dimensionless correlations for spray cone angle and spray tip penetration that provided important insight into the spray breakup and atomization process.