Computational Study of Jet Cavitation Inception Using a Phase Analysis

Cavitation inception in the near-field of high Reynolds number axisymmetric jets is analyzed using a simplified computational model. The model combines an axisymmetric vorticitystreamfunction finite-difference scheme for the simulation of the unsteady flow field. Using a simplified representation, microscopic bubbles are injected at the jet inlet. The motion of these bubbles is tracked in a Lagrangian reference frame by integrating a semi-empirical dynamical equation which accounts for inertial, pressure, drag, and lift forces. Extended calculations are performed for a jet at Reynolds number Re = 2 105 and a ratio of jet shear layer thickness δ to jet radius R equal to δ=R= 0:2. Cavitation inception rates are estimated by extending the analysis in Gopalan et al. (1999), which suggests that the rates may be computed based on the pressure and bubble distributions measured at a constant phase. The computed dependence of the normalized cavitation event rates on cavitation index is consistent with experimental observations. Effects of bubble injection rate and bubble diameter are also examined.