Experimental investigation of the behavior of injected air on the ship bottom and its influence on propeller

Abstract

In recent years, air lubrication system has been attracting attention as a method of reducing carbon dioxide from ship. This method can reduce the frictional resistance through the injected air bubbles on ship bottom, and save energy for propulsion. The authors have investigated the behavior of bubbly flow on the ship bottom and the propeller performance in bubbly flow mainly using the model tests in order to apply the air lubrication system to ship. From the experimental results for module carrier ahead in calm sea, the bubbly flow can cover a wide range of ship bottom, the volume of bubbles flowed into propeller is small and the increase of propeller pressure fluctuation is negligible. However, if the ship is running in oblique flows or in waves, bubbles may flow slightly into the top of propeller and the propeller pressure fluctuation is increased as a result.