On Load Fluctuation Acting on a Blade of Propeller in Waves : 1st Report

Abstract

To make clear the propulsive performance of a ship in waves, it is necessary to know the characteristics of a propeller in waves. The load acting on a propeller in waves consists of the mean value and the fluctuation. It is well known that in moderate sea the former is same as the load acting on a propeller in still water. On the other hand, the load fluctuation acting on a propeller shaft is composed of that acting on each blade of a propeller. And that acting on each blade of the component caused by amplitude modulation with the wave encounter and the propeller revolution frequency. The side band comnonent of the load fluctuation on each blade doesn't appear on the propeller shaft, because blades of the propell are placed at regular intervals. It is important to make clear the load fluctuation acting on not only the propeller shaft but also each blade of the propeller. The load fluctuation acting on a blade of the propeller in waves had already investigated theoretically, but no experimental verification exsists. In consideration of the above, authors investigated on the load fluctuation acting on a blade of the propeller in waves experimentally. The device to measure the load was devised. And tank tests were carried out under the fundamental condition the the open boat was restrained and the propeller was submerged sufficlenty. The data of the load were obtained successfully.