An experimental/numerical assessment over the influence of the dissolved air on the instantaneous characteristics/shedding frequency of cavitating flow

Abstract

The paper reports the numerical/experimental investigations of the cavitation phenomenon in the water flow in the presence of dissolved air. The dissolved air in the water was taken into account in the flow over a Clark Y 11.7% hydrofoil, one of the most common research objects of cavitating flow. The different cavitating flow regimes including the incipient, sheet/cloud and supercavitation were analyzed both numerically and experimentally with different amounts of air dissolved in the water. The dynamics of the cavitating flow, as well as; the main flow parameters, were compared and validated against the experimental data obtained from the closed-loop cavitation tunnel located at the Silesian University of Technology and the literature reports. The FFT analysis of outlet pressure fluctuation and vibration signals were applied to extract the main frequencies of the cavitating flows. The spectrum of vibrations and spectrum of pressure signals at the chamber outlet were in good agreement. The frequency of the main cavitating flow structures increased when the cavitation number increases. It was confirmed that for the tested values of dissolved oxygen in water (2.6 ppm and 5.5 ppm), it was possible to observe a detectable influence of air on cavitation frequencies and noticeable influence on cloud structures.