Numerical Analysis of a Spray Nozzle for Predicting Spray Cone Angle and Pressure Drop

The purpose of this study was the numerical simulation of flow within a spray nozzle for high heat flux spray cooling applications. The particular emphasis was on the prediction of free surface structure after the fluid exits the nozzle. The nozzle top plate had four openings; one at the center and other three at a radial location away from the center placed symmetrically with equal angular spacing between them. In order to perform the simulation as a two-dimensional axisymmetric problem, the three outer holes were replaced by a ring opening with the same flow rate. The top plate remained stationary and swirling was introduced to the fluid at the inlets. Several fluids including FC-77, FC-72, FC-87, water, and methanol running at different flow rates were investigated to observe the effect that their particular properties have on the geometry of the free surface exiting the nozzle. Another variation performed was the geometry of the nozzle. The outer inlet slot was positioned at various radial distances along the top plate. It was observed that a higher flow rate caused an increase in the free surface height and cone angle. For the various radial locations of the outer inlet slot, it was noted that a position at approximately 60-75% of the nozzle radius produced the largest free surface radius as well as the spray cone angle. It was observed that the working fluid properties have very significant effect on the radial location of the free surface and the cone angle. The pressure drop from the inlet of the nozzle to the outlet increased with an increase in the flow rate (or Reynolds number). Minimum pressure drop was found when methanol was used as the working fluid.