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Designs 2018, 2(2), 17; https://doi.org/10.3390/designs2020017

Development of a Butterfly Wind Turbine with Mechanical Over-Speed Control System

1
Faculty of Engineering, Tottori University, 4-101 Koyama-Minami, Tottori 680-8552, Japan
2
Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori 680-8552, Japan
3
Nikkeikin Aluminium Core Technology Co., Ltd., NYK Tennoz Building, No.2-20, 2-chome, Higashi-shinagawa, Shinagawa, Tokyo 140-0002, Japan
4
Enatex Co., Ltd., 2-73 Seidani-cho, Kurayoshi, Tottori 682-0017, Japan
5
SKY Electronics Co., Ltd., 1380-56, Higashionaro, Shimanto-cho Takaoka-gun, Kochi 786-0027, Japan
6
Japan Micro System Co., Ltd., 28-1 Takashima, Yonago, Tottori 689-3536, Japan
7
Tottori Institute of Industrial Technology, 1247 Kusaka, Yonago, Tottori 689-3522, Japan
8
Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580, Japan
*
Author to whom correspondence should be addressed.
Received: 21 May 2018 / Revised: 8 June 2018 / Accepted: 8 June 2018 / Published: 12 June 2018
(This article belongs to the Special Issue Challenges and Progress in Turbomachinery Design)

Abstract

Based on a concept of “cost reduction by large rotor and small generator”, a kind of small vertical axis wind turbine (VAWT) called a butterfly wind turbine (BWT) has been developed with rotor diameter of 7 m and five looped blades. One of the features is a mechanical system which can twist each blade of a VAWT by using the centrifugal force acting on the blades in order to prevent over-speeding of the rotor. An electric power generation system that combines the BWT utilizing the over-speed control system (OCS) with a coreless generator connected to a three-time increasing gear unit is constructed in this study. The performance of the BWT power-generation system is predicted by the blade element momentum (BEM) theory. The final goal of this research is to show the feasibility of the low-cost VAWT power generation system with the proposed OCS. From the results of a series of forcible rotation experiments of the BWT rotor that is driven by an induction motor in very low wind speed condition, it is shown that the twist movement of the blades is improved by the design of the OCS that considers the observed radial force deprived of the centrifugal force and the pre-compression of springs. In the generation experiments with the final design of the OCS, the expected twists of the blades are observed for the first time in strong natural wind speed over 18 m/s. View Full-Text
Keywords: wind-power generation; vertical axis wind turbine; over-speed control system; renewable energy; cost reduction; small-size wind turbine; dryland wind-power generation; vertical axis wind turbine; over-speed control system; renewable energy; cost reduction; small-size wind turbine; dryland
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Hara, Y.; Tagawa, K.; Saito, S.; Shioya, K.; Ono, T.; Makino, K.; Toba, K.; Hirobayashi, T.; Tanaka, Y.; Takashima, K.; Sasaki, S.; Nojima, K.; Yoshida, S. Development of a Butterfly Wind Turbine with Mechanical Over-Speed Control System. Designs 2018, 2, 17.

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