NUMERICAL AND EXPERIMENTAL EVALUATION OF THE OPEN-WATER PERFORMANCE OF A CYCLOIDAL

Paper in proceeding, 2026

In recent years, with the growing demand for more efficient marine propulsion systems, innovative concepts have been introduced and explored. Cycloidal marine propellers with individually controlled blades, inspired by the dynamic motion of a whale’s tail, represent one such concept. In this study, the hydrodynamic performance of a model-scale cycloidal propulsion system with five fins is evaluated in open-water conditions. For this purpose, a three-dimensional geometry consisting of a rotating disk with vertical fins that have pitching motion is numerically simulated through unsteady Reynolds averaged Navier–Stokes (RANS) and the 𝑘–𝜔 SST turbulence model to predict the hydrodynamic performance of the propulsor, including thrust, torque, and power. The simulated results are compared with the experimental data obtained from towing-tank open-water tests. The forces acting on the fins and the flow field characteristics have been examined in detail for a prescribed fins trajectory. The computed and measured hydrodynamic efficiency of the propulsor in model-scale exceeds 68%. Due to the pitching and orbital motions of the fins, each fin undergoes a varying hydrodynamic load throughout a full cycle. These results underscore the critical influence of fin trajectory on thrust and side-force generation. Deviations from the prescribed trajectory can lead to significant side forces.