ABSTRACT:

The aerodynamic performances of an improved Savonius rotor were examined using a wind tunnel of open-blow-out type and compared with those of a basic Savonius rotor which has semi-circular blades. The improved one consists of two stages and each stage has a pair of streamlined J-shaped blades. The tank tests for both the improved and basic Savonius turbines of small size were also conducted using a wave, tank and an OWC (Oscillating Water Column) type wave power converter.

INTRODUCTION

The Wells turbine, one of the self-rectified air turbines, is widely used for OWC (Oscillating Water Column) type wave power devices (Maeda, et al., 1985, Katsuhara, et al., 1987, Miyazaki. et al., 1987). It has excellent aerodynamic performances while has a defect of high manufacturing cost. On the other hand, the Savonius turbine has lower efficiency than the Wells turbine, but it has the advantage of strongness, low cost and ease of manufacture. The purpose of this study is to improve the aerodynamic performances of the Savonius turbine in order to use it as a wave power converter. In this report, the aerodynamic performances of an improved Savonius rotor are examined using a wind tunnel of open-blowout type and compared with those of a basic Savonius rotor which has semi-circular blades. The new rotor consists of two stages and each stage has a pair of streamlined J-shaped blades. The experiments are repeated by changing the number of stages and blades, the type of blade aspect ratio. separation gap ratio and overlap ratio. The tank tests for both an improved and basic Savonius turbines of small size are also conducted using a wave tank of 8.2 m long, 0.8 m wide and 1.6 m deep and an OWC type wave power device of a laboratory scale.

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