Scaling Effects on Cavitation Erosion Pits

In order to clarify the scaling effects on cavitation erosion, erosion pits are carefully measured using a digital image processing technique for four similar flat-hydrofoils with chord length C from 53 mm to 160 mm, corresponding to the cavitation aspects, under similar conditions of cavitation-nuclei size-distribution in the test water, flow velocity, angle of attack and cavitation number. Because the cavitation intensity is correspond to types of cavitation and it is also associated with cavitation-nuclei size-distribution and flow velocity. The erosion intensity I_er, that is defined by the diameter of erosion pits and the pitting rate, is determined to be a power law: I_Er ∝ C. In the average erosion intensity over the hydrofoils, the exponent n is 2, while at the maximum local erosion intensity, the exponent n is 4.5. The erosion pits predominantly result from the vortex cavitation.