Influence of Air Content and Vapor Pressure of Liquids on Cavitation Erosion.

Abstract

Cavitation erosion tests were performed in deaerated and aerated water, in water at various temperatures, in water/ethanol mixtures and in various kinds of organic liquids, the impact loads by collapsing bubbles were measured with the pressure detector. The volume loss curves do not change with the type of water such as deaerated and aerated water, and a similar trend was observed for the results of the pressure distribution. A further increase in the air content decreases the volume loss causing a cushioning effect of bubble collapses. The cavitation erosion increases with increased vapor pressure and reaches a peak, followed by a decrease. The initial increase is due to the increased number of bubbles. Thus, cavitation erosion is mainly affected by both air content a and vapor pressure Pυ of liquid properties. The volume loss rate can be described as Pυ-0.38·e-0.49a. A critical rate air content is found to be 1.6, below which the air content does no longer affect the volume loss rate. It was found that the volume loss rate shows a good correlation with ∑F21/(pc), where F1 is the impact load, p the density and c the sound velocity in the liquid.