The Effect of the External Counter Rotating for the Water Flow Velocity Profile of Twin Propeller System

Abstract

The posture of water flow velocity generated by the rotation of the ship’s propeller needs to be studied to see the performance of the propeller and the potential for scouring that the seabed can cause. This study aims to comprehensively determine the characteristics of the water flow velocity of the External Counter Rotating Twin Propeller (ECRTP) system based on variations in water depth and propeller rpm. The investigation uses an empirical approach, numerical simulations and scale model experiments in the hydrodynamics laboratory to approach the actual water flow velocity. Maximum water flow velocity occurs around the propeller blades and decreases gradually as the horizontal distance to the rear of the propeller increases. In contrast, the water flow velocity on the centerline axis between the propeller axes shows the opposite trend. Each depth has a different water flow velocity posture based on the propeller rpm variation. This research can be applied to improve the performance of a ship’s twin propeller system and anticipate the impact of scour on the seabed.

Keywords

• ship propeller
• twin propeller
• propeller rotation
• seabed scour
• water depth