Measurement of the Velocity Field in Front and behind a Model Propeller in the Cavitation Tunnel with a Laser Velocimeter

Abstract

In naval architecture one of the main problems in propeller design is a phenomenon known as cavitation. In those regions of the flow field where the pressure drops below a determined value (the vapor tension) there appear cavities filled with vapor in the water. The velocity and pressure fields in the propeller region are the result of the joint influence of the propeller action and the ship hull wake. The cavities may appear on the blades of the propeller at a certain angular position; they grow and collapse again as the propeller turns. Precisely the forces appearing during the collapse of these cavities lead to erosion of the material and to damage. Since calculation and prediction methods in this area are still not fully developed, model testing plays an important role in propeller design.