Some Improvements of Ship Power Prediction Method in the IHI Towing Tank

Abstract

For further improvements of the ship power prediction method by model tests, there were many rooms to obtain the accuracy meeting the present designers' demands. In the IHI towing tank, since its establishment in 1966, steady achievements have been done to satisfy their demands. This paper presents almost all of the measures of improvements conducted and the results obtained in IHI, content of which extends from the facility and test practice to the model-ship correlation. Among them, first it is insisted that the reduction of influence of Reynolds number and disturbances such as the residual current in the tank upon the test results is quite effective for increasing accuracy. Second a theoretical estimation method of propeller open-water characteristics is proposed from the view point of correcting the influence of Reynolds number on its performance. Finally taking the influence of interference between Reynolds number of hull and the propeller loading into account, a new method of ship-model correlation for the effective wake is given. As a result, the average errors of model test results decrease less than 1% and the reliability of predicted ship power gets to more than 97%.