NUMERICAL SIMULATION OF ULTRA-HIGH INJECTION DIESEL AND BIODIESEL FUEL SPRAYS

摘要

Computational fluid dynamics (CFD) is utilized in this study to investigate the spray characteristics of diesel and biodiesel fuels. To this end, an Eulerian-Lagrangian multiphase formulation has been used to simulate the spray processes. Fuel is injected into an initially quiescent constant volume chamber. The effect of fuel type, injection pressure and ambient pressure on the spray behaviour has been studied. Macroscopic spray parameters, such as penetration and cone angle, have been investigated, and microscopic features like Sauter mean diameter, local and temporal droplet size distribution have been evaluated to further understand the spray characteristics. Results are compared with experimental data available in the literature. In addition, the interaction characteristics of two merging sprays are studied. The effects of injection point distance and incidence angle on the merged spray penetration, cone angle and Sauter mean diameter have been investigated. Different injection setups have been evaluated and compared in terms of their entrainment qualities. Finally, air motion induced by the liquid dispersion inside the spray is analyzed and connected to the entrainment.