Evaluation of cavitation erosion of a propeller blade surface made of composite materials

Abstract

Cavitation erosion strongly impacts the efficiency and strength of marine propellers. This is more important for propellers made from different types of composite materials. Thus, an investigation of cavitation erosion on the blade surface of composite ship propellers is necessary. A small three-blade propeller was made from fiberglass combined with epoxy, polyester and gelcoat resin. This propeller was tested in a circulating water channel and revolution speed and depth were determined by conditions of cavitation number. Cavitation erosion was observed and evaluated by images, weight loss and cavitation area. The results indicated that the cavitation erosion occurred at regions 0.4 R (Radius) and 0.7 R from the center, and cavitation also occurred randomly on pressure or suction surfaces and leading or trailing edges. Most damaged regions propagated along the circumferential direction of the propeller. Among the blade materials, the Ge-GF blade had the best property. This material had the smallest cavitation area and the most stable cavitation area rate. The Po-GF blade had the worst property with strong progression of the cavitation area, and the Ep-GF blade was of medium quality with a small reduction of the damage area rate. Besides, the depth of the damaged area of the Ge-GF blade was also lower than that of the Ep-GF and Po-GF blade.