Influence of propeller presence and cavitation on a liquid nuclei population

Abstract

The modification of the bubble nuclei population due to the presence of a rotating propeller was modeled numerically using a combined Eulerian - Lagrangian approach. The liquid flow field was solved using a Reynolds Averaged Navier-Stokes (RANS) solver and was improved further using Direct Navier-Stokes Simulations (DNSS) to better capture the wake rollup in the tip-vortex. Bubbles were propagated in the resulting flow field using a Lagrangian approach and computing bubble motion and volume change. Resulting nuclei distribution modification downstream of the propeller for various advance coefficients was studied. The results show that different advance coefficients can result in very different cavitation zones near the propeller as the cavitation number is reduced below the cavitation inception limit. This has a strong effect on the nuclei population downstream of the propeller. We further examine the effect of non-uniformity in the upstream distribution of nuclei, and the effects of gravity and propeller scale on the results. Increasing the scale appears to play a major role in increasing the void fraction downstream.