Theoretical and experimental study of cycloidal propellers

Li, Jin (1991) Theoretical and experimental study of cycloidal propellers. Masters thesis, Memorial University of Newfoundland.

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Abstract

A theoretical and experimental study was made on cycloidal propellers. -- Experiments were done on a model trochoidal propeller with a pitch ratio of 2.924π in a cavitation tunnel in the Institute for Marine Dynamics (NRC). Problems which caused unreliable test results from a previous experimental study of the model propeller were examined. A mal-functioned torque transducer was replaced. Problems in the measurement of hydrodynamic torque and in calibration tests were analysed and effective ways to solve those problems were used in the present experimental study. Reliable test results for this model were obtained for propeller revolution speeds of 100, 150, 200 RPM. -- Mendenhall and Spangler's discrete vortex method of studying cycloidal propeller performance was modified so that (a) an angle of attack method was used to calculate effects of wake and other blades; (b) the modeling of dynamic stall effects were included; (c) three-dimensional effects of the blades were included. The theoretical results were compared with the experimental data from the present tests and from published results for cycloidal propellers with different pitch ratios and number of blade. It was found that the three dimensional correction method improved the predicted propeller performance at pitch ratios greater than π. The two dimensional model using the angle of attack method gave better prediction of propeller performance than other models at pitch ratios smaller than π. The effectiveness of these models is discussed.

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