NUMERICAL STUDY OF INLET AND GEOMETRY EFFECTS ON DISCHARGE COEFFICIENTS FOR LIQUID JET EMANATING FROM A PLAIN-ORIFICE ATOMIZER

摘要

A computational model for flow in a plain-orifice atomizer is established to examine the inlet and geometry effects on discharge coefficients. The volume of fluid (VOF) method with finite volume formulation was employed to capture the liquid/gas interface. A continuum Surface Force (CSF) model was adopted to model the surface tension. The body-fitted coordinate system was used to facilitate the configuration of the atomizer. The influences of the inlet chamfer angle, the orifice length/diameter ratio, the Reynolds number, and the inlet turbulence intensity are analyzed. It is found that the optimum discharge coefficient occurs at a chamfer angle of about 50°. The discharge coefficient at first increases with the increase in the orifice length/diameter ratio and then it decreases. The discharge coefficient increases with the increase in the Reynolds number up to Re = 40000, after which it remains sensibly constant. The influence of the inlet turbulence intensity on discharge coefficient is not significant, especially for a longer orifice.