Engineering design methods for cavitation reactors II: Hydrodynamic cavitation

Abstract

The bubble behavior and hence the pressure generated at the collapse of the cavity for hydrodynamic cavitation depends on the operating conditions and geometry of the mechanical constriction generating cavitation. The effect of operating parameters such as inlet pressure through the system's orifice, initial cavity size, and the indirect effect of the hole diameter (it affects the frequency of turbulence in the vicinity of the orifice) on the bubble behavior was numerically studied. The bubble dynamics were simulated in two stages considering: Rayleigh-Plesset equation up to the point of bubble wall velocity = 1,500 m/s; then the compressibility of the medium using the equation of Tomita and Shima. An empirical correlation was developed to predict the collapse pressure generated as a function of just mentioned parameters. The trends in the magnitudes of collapse pressure match the observed experimental trends for cavitation-induced reactions. The work is an extension of the earlier analysis done for the sonochemical reactors. Some recommendations are also suggested for the design of hydrodynamic cavitation reactors based on the simulations.