Pages 97-103
Four propellers with different skew angle distribution and constant pitch distributions are selected in order to clarify the skew effects on hydrodynamic characteristics of propeller performance. Using these propellers, the effects of the skew distributions on propeller open-water characteristics, cavity extents and cavity thickness distributions on the suction side of the propeller blades are investigated by towing tank tests and cavitation tests in uniform flow. The test results show that the increase of skew angle induce the increase of thrust and torque coefficient, but only slight changes in efficiency. The cavity extent and thickness near the blade tip also increase in proportion to the increse of skew angle. The potential-based vortex lattice calculations have been done to obtain detail informations from the calculated flow field around the propeller blades in non-cavitating condition. Cavity extents and thickness distributions are also calculated by linearized free streamline theory and compared with the experimental results. These results show that the propeller loading near the blade tip increases and the loading near the root decreases as the increase of skew angle. The calculated cavity thickness distributions near the blade tip are underestimated but those of inner part are overestimated.
