Numerical analysis of propellers for electric boats using computational fluid dynamics modelling

Abstract

In the maritime industry, propellers are the most commonly used form of propulsion and are core to the optimum performance of a ship. As marine propellers have complicated geometries, the flow around the propeller is also complicated. Generally, the performance characteristics of a propeller are determined and analysed by experiments like open water and self-propulsion scale model tests which are costly and time-consuming at the initial design stage. In this study, the CFD simulations were performed to evaluate propeller performance. Three Wageningen B-series propellers with varying Expanded Area Ratios (EAR) were modelled with respect to some design constraints, such as ship speed and rotational velocity. The performance of the hydrodynamic coefficients, thrust, torque and open water efficiency are then analysed. These characteristics are then validated against experimental data obtained from the Netherlands Ship Model Basin open water test in Wageningen and used to investigate the flow behaviour. The analysis considers the Multiple Reference Frame (MRF) model. This research aims to provide a well-founded framework for applying CFD in the analysis and selection of Wageningen B-series propellers, as well as investigating the relationship between EAR, flow behaviour, thrust coefficient, and torque coefficient for electric boats. The results showed that a lower thrust and torque coefficient manifested in improved flow behaviour, increasing efficiency by up to 62%. In addition, the outcome revealed that the lower expanded area ratio of 0.6 is more suitable for electric boats, creating a larger pressure difference of 1.079 MPa and generating extra potential thrust at the same advance ratio, which leads to greater open water efficiency.