On the Method of Cavitation Tests for Prediction of Tip Erosion of Propeller

概要

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Tip erosion and bent trailing edge are found on most of the propellers of single screw ships. It is well known that such damages are due to unsteady cavitation, but they are not always predicted by the cavitation tests on the model propellers in non-uniform flow. Attempts were made therefore to improve the testing techniques to achieve a better agreement between the model test results and the performance of the ship propellers. Two tanker propellers were selected representing those which suffered from "slight" and "moderate" damages. They were tested under wide range of propeller loading and cavitation number in various wake distributions. As a result it was found that the steepness of high wake zone plays an important role on the occurrence of the cloud cavitation which results in the cavitation damage and that the model wake distributions, which have been used in most of the cavitation tunnels, are not steep enough to simulate the cavitation damage. For prediction of tip erosion and bent trailing edge of ship propellers, it is recommended that the model propellers should be tested in the wake distributions three or four times steeper than the model wake and the occurrence of cloud cavitation should be observed.
社団法人日本船舶海洋工学会の論文