An investigation of the effects of Reynolds number on the performance of 0.6m impulse turbines for different hub to tip ratios.

This paper presents the account of an investigation of the effects of Reynolds number on the performance of 0.6m Impulse turbines with fixed guide vanes for different hub to tip ratios of 0.6 and 0.7. This work is part of the research to establish an optimum value of hub to tip ratio for the said turbine for its application for an OWC based wave energy power conversion device. A wide range of flow rates was tested for both turbines. Depending on the operating range of the unidirectional steady flow test rig, a Reynolds number range of 0.46 x 10(5) - 1.19 x 10(5) for 0.6 H/T ratio rotor and 0.51 x 10(5) - 1.32 x 10(5) for 0.7 H/T ratio rotor was achieved respectively, at peak efficiency. The results show that both turbines reach a maximum efficiency point gradually, after which there is a slight drop in the peak efficiency and eventually it stabilizes for higher Reynolds numbers. It was also observed that the 0.6 H/T ratio turbine performance is better than the 0.7 H/T ratio turbine and gives a wide range of Reynolds number where efficiency is higher. The objective of this paper is to report the details of the experimental work carried out for this investigation and establish the effects of Reynolds number on the performance of Impulse turbines with different hub to tip ratios.