A study on correlation of vortex cavitation noise of propeller measured in model experiments and full scale

Abstract

A correlation of noise radiated from sheet or bubble cavitation occurring on propeller blade surface is well established. On the other hand, the correlation is not clear on noise radiated from vortex cavitation occurring at a distance from propeller blade. In the present paper, cavitation patterns and noise characteristics of the propeller accompanying only the vortex cavitation were investigated by model tests in a cavitation tunnel and full-scale measurements in order to know the correlation of noise radiated from vortex cavitation of propeller. Comparisons of full-scale cavitation pattern with model scale showed that vortex cavitation depends on not only cavitation number but also Reynolds number. Predicted noise level from model tests using scaling formulas of cavitation noise agreed well with full-scale measurements in the case where vortex cavitation patterns in model and full scale are similar. Cavitation number may vary at Reynolds number to the 0.15 power to keep similarity of pattern of vortex cavitation.