The design and energy saving effect prediction of rudder-bulb-fin device based on CFD and model test

Abstract

Recent developments in Computational Fluid Dynamics (CFD) and high-performance computer hardware have made it possible to design Energy Saving Devices (ESDs) using numerical methods. The present work investigates the influence of rudder bulb diameter, thrust fin; span, chord length and angle of attack on propulsive efficiency. In order to increase computational efficiency, a hypothesis was developed and a quick estimate method for design parameters and the optimization procedure. Bare hull resistance, propeller open water performance and interaction of hull-propeller-rudder simulations were carried out using CFD code to solve Reynolds Averaged Navier-Stokes (RANS) equations. A validation study shows a good agreement between the CFD and experimental data. Model tests were carried out using optimum parameters for rudder bulb and rudder attached thrust fins. Comparison of the propulsive efficiency between the ship with the conventional rudder and ship with the optimized rudder-bulb-fin device was done. The model test predicted energy gains of 2.18% compared to 2.63% gains predicted by the CFD method. This study would be useful during design and optimization of rudder-bulb-fin.