Mechanics of Cavitation

A summary review of the knowledge related to the mechanism of cavitation is presented. Stability criteria for a spherical gas nucleus as well as the possible origins of such nuclei are examined. The critical pressure for cavity instability depends on the type and size of nuclei present in the flow. This critical pressure in large hydraulic structures usually be taken as the liquid vapor pressure but for small models tested in laboratory facilities, the critical pressure can be much less than vapor pressure. For streamlined bodies with unseparated boundary layers, the conditions for cavitation inception may be predicted by setting the minimum boundary pressure equal to the critical pressure. This method is usually inadequate for the case of bodies with separated flows; however, a method of conservatively estimating the conditions for cavitation inception in separated flows is presented. The dynamics of a collapsing cavity are examined, and the influence of the boundary layer on the types of cavities formed and the resulting damage is also reviewed. The scale effects suggested by the mechanics of the cavitation process are presented.