Yasuyuki Nemoto

A Study of the Twisted Sweeney-Type Wind Turbine

The late professor Thomas E. Sweeney of Princeton University proposed the concept of vertical-axis wind turbines driven by drag/lift force in 1973. The authors fabricated Twisted-Sweeney type wind turbines, based on the Sweeney type wind turbine, to improve the performance and to enhance its external appearances. From experimental testing of this wind turbine in a wind tunnel, the following conclusions were deduced.

Wind Tunnel Analysis of Concentrators for Augmented Wind Turbines

Various power augmentation systems have been studied to improve the performance of wind rotors by increasing the energy density of the wind. One of them is the ducted augmentation system. However, most of the studies of the ducted rotor concern the effect of the diffuser [1] [2] while little research has been done concerning the concentrator (nozzle). This paper analyses the effect of the concentrator and its optimum design. The effect of power augmentation is increased if (a) the position of the rotor is correctly behind the outlet of the concentrator, (b) the outlet diameter of the concentrator is smaller than the rotor diameter, and

Historical Evaluation of the Yamada-Type Wind Turbine

The Yamada-type wind turbine was the sole mass produced small scale wind turbine produced during the mid Showa period of Japan. The Yamada-type wind turbines were used all over Japan, particularly in the north Hokkaido and Tohoku area, in the era of post World War II. Although it is thought that the experience and knowledge derived from them is very useful for further development of small scale wind turbines, there are few reports on them. In this paper, the authors investigate the Yamada-type wind turbine and Mr. Yamada himself-from the aspect of history of technology.

Experimental Study of a Vertical-axis Sailwing Water-pumping System

A vertical-axis ‘sailwing’ windmill is developed for autonomous wind-powered water-pumping. To determine the optimum design configuration of the rotor, various model test were carried out in a wind tunnel. The variable parameters were the shape and number of sails. The results favoured a rectangular shape with four sails, as fabricated for tests. Experimental studies determined the starting characteristics and water discharge capability of the integrated V-axis sailwing water-pumping system. The result shows that the system has self-starting characteristics and could pump 25 l/min. of water at 6 m/s wind speed.

Experimental Study of a Pinwheel-Type Wind Turbine

Pinwheels have been familiar as toys for hundreds of years. Not only do they have an attractive appearance, they can also be fabricated from just one piece of plate. Application is possible, e.g. for education and architectural design. The purpose of this paper is to clarify the characteristics and to determine the optimum design configuration of pinwheel type wind turbines. The authors fabricated the test rotors with various shapes and carried out the experiment in a wind tunnel. As a result, the following facts were obtained: (1) Power coefficient with the traditional 4 blades has, CPmax = 0.17 at λ = 2. (2) High tip speed is obtained by cutting the frontal area of pinwheel. Tip speed ratio at no load can be easily changed from λ = 3 to 6 by changing the cutting area. Maximum power coefficient CPmax = 0.22 was obtained at tip speed ratio λ = 3.5. (3) Increased torque is obtained by cutting the edge area of the pinwheel. Tip speed ratio at no load can be easily changed from λ = 2 to 3, and torque coefficient can be easily changed from CQmax = 0.15 to 0.25, by changing the cut area.