On flow regime inside plain-orifice nozzle

Abstract

The plain-orifice is the most common type of atomizer. The flow regime inside plain-orifice nozzle has a tremendous effect on the external spray. At present, the judgement method of the flow pattern is not uniform. The purpose of this study is to numerically investigate the relationship between the change of flow pattern, the ratio of nozzle length and nozzle diameter (L/d), the ratio of nozzle radius of the entrance and nozzle diameter (r/d) in plain-orifice nozzle. The computational fluid dynamics (CFD) code FLUENT was used to perform the numerical simulation of the cavitating flow and hydraulic flip in the nozzles. In this paper, the relationship between the change of flow pattern, r/d and L/d was obtained, and the relation curves between L/d and r/d were plotted, and a new model of flow pattern was obtained. The model established in this paper is more accurate than the empirical model to judge the change of flow pattern. The new model is helpful to modify the existing empirical model. According to the relationship, the researcher can use the method of reasonably adjusting the relationship between the nozzle structure and operating conditions to avoid the generation of hydraulic flip, and to get better atomization effect.