Cavitation of Cycloidal Propulsors Through CFD Analyses

Cycloidal propellers (CPs) are an unconventional propulsion system that combines high manoeuvrability with complex unsteady hydrodynamics, making them attractive for specialized marine applications such as dynamic positioning. Despite their potential, only limited experimental and numerical data exist, and almost no information is available on cavitation phenomena and their effect on performance, despite the large angles of attack typically experienced by CP blades. To address this gap, the present study numerically investigates CP performance with emphasis on thrust generation, efficiency, and cavitation dynamics. A RANS-based CFD approach coupled with a simplified cavity model is used to capture the unsteady flow structures and vapor cavity evolution around the rotating blades. Results highlight the role of eccentricity, of the pivot point location as well as of the number of blades on non-cavitating and cavitating performances, investigated at several advance coefficients and cavitation indexes. Comparisons between three- and six-blade configurations further reveal how blade count and cascade effects modulate force peaks and bubble transitions. The findings contribute to understanding the behaviour of CP under realistic operating conditions, offering guidance for future developments in this type of high-performance propulsion system.