Numerical Prediction of Tip Vortex Cavitation Noise Of Underwater Propellers Using RANS Solver, Bubble Dynamics And Acoustic Analogy

In this study, tip-cavitation cavitation noise of underwater propeller is predicted using one-way coupling hybrid method consisting of RANS solvers, bubble dynamics model and Acoustic Analogy. The propellers are newly designed and manufactured to study effects of sweep angle on cavitation noise. Because it is generally challenging to capture the vortex structure by using the RANS solver due to its numerical damping, tip-vortex structure is reconstructed by applying the vortex model in association with the RANS flow field. Vortex core location is identified using the minimum λ2 criterion. The magnitude of modeled vortex is determined by using the circulation of flow field near tip of propeller blades. Then, bubble dynamics model is employed to predict cavitation. The initial nuclei distribution and critical pressure are determined to represent the water quality. The Keller-Herring equation which includes the liquid compressibility and the bubble trajectory equation are solved to predict the bubble motion of each nuclei in the flow field. Finally, cavitation noise is predicted by considering each of nuclei as monopole source. The validity of the present numerical approach is confirmed by comparing the numerical with the experimental results.