Hydrodynamic analysis of cycloidal propellers

The working principle of a cycloidal propeller is complicated given that its blades are engaged in multi- degrees of freedom (DOF) motions. The instantaneous forces developed on the blades were studied to analyse the hydrodynamic characteristics of the propeller. The results of this study show that the oscillating centre distributed in the chordwise direction will exert significant effects on the fluctuation of the thrust produced by the cycloidal propeller. It will also significantly affect the average value of the thrust and efficiency. In addition, the effect of eccentricity on the thrust produced by the cycloidal propeller was also analysed. A higher eccentricity will considerably increase the thrust, and will make the curve of hydrodynamic characteristics steeper. Therefore, for the design of the cycloidal propeller, it is crucial to choose an appropriate eccentric point and an eccentricity value so as to balance the magnitude of thrust and its fluctuation.