Comparison of a Cavitation Susceptibility Meter and Holography for Nuclei Detection in Liquids

Abstract

This work compares the results obtained from a Cavitation Susceptibility Meter (CSM) and from direct holographic observations for the detection of cavitation nuclei in tap water samples. The CSM uses a cavitating venturi tube to measure the concentration of active cavitation nuclei as a function of the pressure at the venturi throat, while the holographic system measures the nuclei concentration size distribution. Microbubbles are used as the dominant type of cavitation nuclei. The data from the two nuclei detection methods are then compared and interpreted in view of the expected dynamic behavior of microbubbles in the CSM venturi throat. Both results show that the concentration of active cavitation nuclei initially increases exponentially with the applied tension, reaches a maximum and remains nearly constant thereafter when few additional nuclei are left to cavitate. In its current configuration the CSM tends to underestimate the concentration of active cavitation nuclei and to overestimate the value of the nuclei critical pressure as a consequence of sensitivity limitations and interference effects between the cavities.