ABSTRACT:

Experimental investigations directed towards improving the overall characteristics of the selfrect1fying turbine for wave power generator are reported. First, biplane axial turbines with various setting angles have been manufactured and tested in a computer-controlled wind tunnel, which can simulate arbitrary osc11lating flows. The effects of the blade setting angle, gap-to-chord ratio, solidity and arrangement of the biplane rotor on the turbine performance have been examined. The results have been compared with those of the air turbine with self-pitchcontrolled blades and biplane Wells turbine from the viewpoints of the running characteristics and starting character1stics. As the results, a suitable choice of the design factors has been suggested. Next, the hysteretic characteristics of the turbine has been examined to establish a design method. The hysteres1s is more sens1tive to the solidity and arrangement of the b1plane rotor and less sensitive to the sett1ng angle and gap-to-chord ratio.

INTRODUCTION

One of the renewable energy sources" which has received close attention is energy contained in ocean waves. There are various techniques for extraction of energy from waves. Some are based on a power train system of hydro-pneumatic-mechanical-electrical energy conversion in which an air turb1ne is an essent1al element. The Wells turbine for the wave power generator 1S a self-rectifY1ng air turbine which is available for an energy converS10n in an oscillating water-air column w1thout any rectifying valve. There are several reports on the performance of the Wells turbine both on the starting and running characterist1cs (Raghunathan, et al., 1985, 1986, Inoue, et al., 1986a, 1986b, Kaneko, et al., 1986, Setoguchi, et al., 1986). According to these results, the Wells turbine has inherent disadvantages; low efficiency, poor starting characteristics and high axial thrust in comparison w1th the conventional a1r turb1nes. Therefore, it is necessary to improve these points in order to develop a practical wave power generator system.

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