Experimental analysis of blade root cavitation erosion on set of model propellers

The objective of the present study is to investigate by model tests the erosion caused by blade root cavitation for a set of three marine propellers. Experiments have been carried out using soft paint technique together with cavitation observations in the UNIGE cavitation tunnel. Three standard cameras and one high speed camera have been used to observe the damage patterns and cavitation dynamics, respectively. Standard cameras are fixed on the top of test section to continuously monitor the effect of erosion damage on the blade root, the high-speed camera has been placed at different positions to investigate detailed evolution and collapse of bubbles on pressure and suction side of propeller blades. Soft paint results showing damages pattern have been analysed simultaneously with the high speed videos, and showed remarkable agreement between the occurrence of damage on the blades and the bubble collapse of cavitation. The proposed methodology allows comparing different propellers in terms of cavitation aggressiveness. The comparison of these results with full-scale data provides useful indications to propeller designers when root cavitation cannot be avoided.