Effects of Nozzle Geometry on Cavitation in Nozzles of Pressure Atomizers

Abstract

The effects of nozzle geometry on cavitation in the nozzle of pressure atomizers and the liquid jet are examined using various two-dimensional (2D) nozzles with different geometries. Then, whether or not the conventional cavitation numbers can be used to predict the formation of supercavitation, in which liquid jet atomization is enhanced, is examined. As a result, we confirm that (1) the thickness of the cavitation zone increases with the ratio Cu of the cross-sectional area upstream of the nozzle to that of the nozzle, (2) the spray angle increases with Cu, (3) the formation of supercavitation can be predicted using the cavitation number σc' in which the effects of the flow contraction and the frictional pressure drop are taken into account, and (4) the conventional cavitation numbers σ, σ2 and σ3 cannot predict the formation of supercavitation in nozzles with different geometries.