A Prediction Method of Ship Performances Using the Data of Velocity Field of Flow in the Propeller Disk behind the Full

Abstract

In this paper the author describes a new prediction method of ship performances. This method is based on a mathematical model of the hydrodynamical action of a propeller in the given velocity field of the flow in the propeller disk. The thrust and torque of model propeller behind the model ship can becalculated by providing the measured wake patterns behind the model ship and assigning the rovolutions per second of the propeller. Simulating this process, when the wake patterns of the full scale ship are estimated by Sasajima-Tanaka method, thrust, torque and power generated by the actual propeller behind the full scale ship are predicted. For one numerical example, the predicted results of a large oil tanker have shown the good agreement with its trial resuls. By this method, the full scale wake fraction need not to bo estimated by practical means. Subsequently, the effects of non-uniformity of flow on propulsion factors, particularly effective wake fraction and relative rotative efficiency, have been made clear, and the scale effect on propulsion factors have been taken into account of itself.