Design and Optimization of Rudder Bulb Based on Cfd and Genetic Algorithm

Abstract

With the mandatory implementation of Energy Efficiency Design Index (EEDI), higher requirements are put forward on the energy-saving capacity of ships. The fact that 15-30% propulsion energy is lost in the wake inspires people to exploit the measures for improving energy-saving capacity of ships to meet the EEDI requirements by recovering the lost energy, such as through rudder bulb. For this purpose, the design and optimization of rudder bulb appears to be particularly important. This paper aims to propose a design and optimization framework for rudder bulb to find a high-performance energy-saving device suitable for the propulsion system of a ship. A Computational Fluid Dynamics (CFD) method is applied to predict the hydrodynamic performance of rudder bulbs, and the numerical results are compared with available experimental data, which shows satisfactory agreement. Then a Design of Experiment (DOE) method is used to conduct sensitivity analysis of design variables, and a Genetic Algorithm (GA) approach is adopted in search of the optimal design of rudder bulb. The flow field around the propulsion system with different rudder bulbs is presented and analysed. It shows that a 3.66% increase in efficiency is achieved by the optimal rudder bulb design via GA approach.

Keywords: rudder bulb, design and optimization, Computational Fluid Dynamics, Design of Experiment, genetic algorithm