Hydrodynamic Performance of a Cycloidal Propulsor in Model-Scale and Full-Scale

Paper in proceeding, 2026

A controlled-blade cycloidal propulsion system is an innovative marine propulsor inspired by the dynamic motion of a whale’s tail, combining advanced hydrodynamics, smart control, and sustainable design in one system, with a unique feature of blade rotation and pitching via a trajectory function. In this study, the effect of scale on the hydrodynamic performance of a cycloidal propulsor with a trajectory function is evaluated in open-water conditions. For
this purpose, a three-dimensional geometry consisting of a rotating disk with vertical blades that have pitching motions is numerically simulated through unsteady Reynolds-averaged Navier-Stokes (RANS) and k-ω SST turbulence model to predict hydrodynamic performance. The trajectory function defines the prescribed pitching motion of each blade during one orbital cycle. This function remains fixed and is not influenced by the surrounding flow field. However, its hydrodynamic effects differ considerably between model-scale and full-scale conditions. Variations of Reynolds number in model-scale and full-scale during one complete orbit are investigated. Differences in Reynolds numbers across the two scales lead to variations in viscous and unsteady flow behaviors, which in turn influence the overall thrust and torque trends. The current research compares the performance of the cycloidal propulsor in model scale and in full-scale through analysing the open-water curves as well as pressure and shear force variations across these scales.