Vibratory Hull Forces Induced by Cavitating Propellers




This paper deals with the influence of propeller cavitation on hydrodynamic hull excitation. Recent investigations have established that cavitation on the propeller considerably increases the pressure fluctuations on the afterbody of the hull. Here, the significance of the findings of previous investigations is examined and an attempt is made to assess the dependence of propeller cavitation-induced fluctuating hull pressures on propeller geometry, propeller loading, and the type and extent of cavitation. To this end a number of Wageningen B-Series model propellers were tested in the large cavitation tunnel of the Netherlands Ship Model Basin, varying both the number of blades and the blade area ratio. The wake of a large and full single-screw tanker was simulated by building an appropriate ship model into the cavitation tunnel. At three positions on the afterbody of the model ship the propeller-induced pressure fluctuations were measured for various propeller loadings and values of the cavitation number. The observed cavitation phenomena were photographed and sketched.