Prediction method of propeller tip vortex cavitation inception based on bubble dynamics models and change-point detection

Abstract

Due to the scale effect, tip vortex cavitation (TVC) is usually the first type of cavitation in real ship propellers. There is an urgent need in the engineering field for accurate prediction of the TVC inception. The traditional homogeneous flow cavitation model fails to accurately simulate the incipient cavitation flow because it ignores the nuclei evolution. To address this issue, a new method based on the Euler-Lagrange (E-L) frame bubble dynamics model was proposed to simulate propeller TVC inception. This method considers the compressibility of the liquid and the dynamic effects of nuclei motion, growth, and collapse, enabling precise simulation of the incipient cavitation field in propeller tip vortices. Furthermore, criteria for determining TVC inception were established by detecting the change point of the number of incipient cavitation bubbles. For a 7-blades high-skewed propeller, this method improved prediction accuracy by over 20 % compared to traditional methods. Finally, the dynamic evolution of microscopic nuclei motion, growth, and collapse clarified the cavitation inception mechanism. The influence of tip vortex flow on nuclei entrainment and capture under different advance coefficients was analyzed, providing guidance for accurate TVC inception prediction in engineering and ship critical speed.