ABSTRACT
Hydrodynamic cavitation occurs and spreads in a jet of water flowing through a channel whose geometry causes the appropriate static pressure variations in the flow (Brennen, 1995, Bagieński, 1998, Gogate et al., 2000). During the process of such cavitation three characteristic, consecutive stages can be distinguished: − The Cavitation Inception Stage-the formation of cavitation bubbles on
a macro-scale with dimensions in microns. Under practical conditions, the basis for bubble formation is the existence of cavitation nuclei in watergas-filled or vapour-filled micro-bubbles or alternatively solid micro-particles
− Bubble Growth-the growth of bubbles or other enclosed volumes called cavities, the expansion of these volumes is the consequence of the loss of equilibrium between the internal and external forces at the phase transition boundary layer between the liquid and gaseous phases
− The Dissolution Stage-the collapse of cavitation regions, being of an implosive nature, due to a rapid increase in external forces acting on them From a physical point of view, three characteristic types (forms) of cavita-
tion can be distinguished in water: 1. Vaporous cavitation 2. Gas-vapour cavitation 3. Gaseous cavitation
Vaporous cavitation relates to a homogenous material, which during cavitation undergoes a series of phase transition changes from liquid to vapour and from vapour to liquid. For this type, the cavitation zones are filled with wet saturated vapour-remaining in contact with the liquid from which they originated.
