Novel optimized layout for Flettner rotors based on reuse of wake energy

Abstract

The application of wind-assisted propulsion contributes to the reduction of pollutant emissions and the protection of the environment. A novel approach for the reuse of wake energy was established to optimize the layout of Flettner rotors based on the idea of migrating geese that fly in a V-shape formation to save energy. The new layout improves the aerodynamic performance of the two-rotor system compared to two separate rotors, and saves deck space. The wake structure, interaction effects, and force coefficients of rotors in the upstream rotor wake were determined in Fluent. A response surface model was developed to describe the relationship between the lift coefficient as the optimization object and layout by using the Kriging method. Subsequently, the particle swarm optimization (PSO) algorithm was used to determine the optimal position of the downstream rotor. Consequently, the downstream rotor is mounted on the high flow side of the upstream rotor. The resulting two-rotor system exhibits a significantly higher average lift coefficient, it has increased to 5.260, which corresponds to an increase of 22.98% from the reference value of 4.277. Improvements in the lift coefficient of the Flettner rotor are beneficial to the capture of wind energy by wind-assisted propulsion vessels.