Multi-phase flow modeling of tip vortex local flow of marine propellers

Multi-phase flow simulations of E779A and DTMB5168 propellers´ tip vortex flow field are conducted to qualify the improved Sauer cavitation model in propeller tip vortex local flows prediction, under non-cavitation and initial inception conditions. Mesh refinement strategies pointing to blocking-structured and stream-adaptive grid for vortex flow are concluded in this process. The models account for the effects of mass and volume fraction of the noncondensable gas (NCG) and the turbulence on both cavitation inception and bubble growth by means of mixture density formula and phase-changing threshold pressure formula explicitly. With comparison to the experiments, open water performances of two propellers are both predicted satisfactory with cavitation model un-activated. The simulated propeller cavity pattern and cavitating area under moderately cavitation level are very close to the measurements after cavitation model activated. The circumferentially averaged axial, circumferential and radial velocity components on wake cross plane correspond very well with the measurements outer 0.9R radius. The predicted peaks of three velocity component variation with circumferential theta show a discrepancy to the tests up to about 5%, 40% and 20% respectively at 0.92R, and a maximum prediction error smaller than 10% at 0.7R. The predicted trajectories of tip vortex core are very close to the experiment at front of the downstream 0.3R wake plane, wherein a bigger predicted core radius than the tests further away. Results above show that the mesh strategies introduced in conjunction with the adopted numerical models are positive and beneficial to the vortex-dominated flow of propeller.