Table of Contents Author Guidelines Submit a Manuscript
International Journal of Rotating Machinery
Volume 2012, Article ID 910940, 12 pages
Research Article

Moment of Inertia Dependence of Vertical Axis Wind Turbines in Pulsating Winds

1Department of Mechanical and Aerospace Engineering, Graduate School of Engineering, Tottori University, 4-101 Minami, Koyama-cho, Tottori 680-8552, Japan
2Nagoya Industrial Science Research Institute, 306 Yuta, Obata-cho, Ise, Mie 519-0506, Japan

Received 5 October 2011; Revised 19 January 2012; Accepted 2 February 2012

Academic Editor: J.-C. Han

Copyright © 2012 Yutaka Hara et al. 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.


Vertical Axis Wind Turbines (VAWTs) are unaffected by changes in wind direction, and they have a simple structure and the potential for high efficiency due to their lift driving force. However, VAWTs are affected by changes in wind speed, owing to effects originating from the moment of inertia. In this study, changes in the rotational speed of a small VAWT in pulsating wind, generated by an unsteady wind tunnel, are investigated by varying the wind cycle and amplitude parameters. It is shown that the responses observed experimentally agree with simulations based on torque characteristics obtained under steady rotational conditions. Additionally, a simple equation expressing the relationship between the rotational change width and amplitude of the pulsating wind is presented. The energy efficiency in a pulsating wind remains constant with changes in both the moment of inertia and the wind cycle; however, the energy efficiency decreases when the wind amplitude is large.