Abstract: Objectives The toroidal propeller, as an unconventional propeller form that controls tip flow and enhances tip stiffness through its tip geometry, has limited published literature on hydrodynamic performance analysis and experimental validation data for this new type of toroidal propeller both domestically and internationally.MethodTo study the flow characteristics of the special toroidal structure at the tip of the toroidal propeller, firstly, numerical simulation methods for the uniform flow hydrodynamic performance of a five-bladed toroidal propeller were developed using the STAR-CCM+ viscous flow CFD software. The impact of mesh density on the calculation results was analyzed. Subsequently, hydrodynamic measurement model tests were conducted on the toroidal propeller model in a cavitation tunnel, obtaining hydrodynamic validation data for the toroidal propeller and comparing the results of numerical calculations with model tests. Finally, the pitch distribution, circulation distribution, and trailing vortex structure of the toroidal propeller were analyzed.ResultsThe study indicates that the established numerical simulation method for the toroidal propeller has an error within 4%, achieving substantial agreement with the expected results. Analysis of the load and flow characteristics of the toroidal propeller reveals that, compared to conventional propellers, it can sustain a certain level of load at the tip, resulting in a continuous non-zero circulation at the tip. The ring structure of the propeller generates different flows inside and outside the torus, creating a low-pressure area within the ring with "water-suction" properties. Additionally, the toroidal structure leads to a continuously evolving vortex core shape and structure in the wake of the toroidal propeller.ConclusionThe numerical simulation method established in this paper can accurately predict the hydrodynamic performance of the toroidal propeller. The findings from the model test study provide valuable data support for the design verification of domestic toroidal propellers. The flow characteristics at the tip, attributed to the geometric features of the toroidal propeller discovered through numerical simulation and load-flow analysis, can lay the foundation for further simulation optimization and parameter studies of toroidal propellers. Key words：CFD；Uniform flow test；Toroidal propeller；Trailing vortex structure