Topology optimization of low-friction painting distribution on a marine propeller

Abstract

Following the United Nations 2030 Agenda to achieve a better and more sustainable future, there is an interest in new energy efficiency technologies to address emissions from international maritime shipping. A large portion of the available research focused on paints that reduce the fouling and friction of the hulls of these vessels, such as hydrophobic paints. Yet, research applied to propellers is smaller when compared to hulls. Covering the blade surface with hydrophobic paint behavior changes the drag of the propeller and, consequently, the hydrodynamic efficiency. However, covering a blade may adversely affect the flow in certain regions, reducing the propeller performance. This paper studies a practical application of the super-hydrophobic surface (SHS) pattern distribution on a marine propeller using the topology optimization method to determine regions where the application of surface treatment leads to improved propeller efficiency. The numerical method is developed to model the turbulent flow condition with the behavior of the boundary layer that imposes the low-friction/hydrophobicity effect to predict the performance of a coated propeller. To evaluate the proposed method, firstly, a fully covered blade is simulated for several hydrophobic conditions and then the topology optimization is conducted. Despite the SHS behavior being simplified by adopting the slip length model, the obtained optimization results show the regions to be prioritized in order to maximize the hydrodynamic efficiency.