Numerical Investigation of the Propulsive Efficiency of a Containership under Load Variation

Abstract

The International Towing Tank Conference (ITTC) suggests that determining the variations of propulsion efficiency can be achieved by model tests that may be costly and inefficient. This is the reason why this paper investigates the variation of propulsion factors under various ship loading conditions by computational fluid dynamics (CFD). This study proposed a non-iterative method for load variation tests that reduced the computational time. The CFD software Star-CCM+ was used to solve the transient free-surface Reynolds-averaged Navier–Stokes equations. To further reduce the computational time, the propeller was modeled using the actuator disk method. The resistance augmentation, wake fraction, and propeller efficiency of a container ship model KCS with propeller KP505 were studied. These values were used to calculate the load variation coefficient of the shaft revolution speed ζN and load variation coefficient of the delivered power ζP at full scale. The results showed that as the resistance increased, the rotation rate correspondingly increased to maintain the service speed. As the ship resistance increased, the hull and open water efficiencies decreased, and when the actuator disk model assumed a relative rotative efficiency of 1.0, the quasi-propulsion efficiency also decreased.