Effect of radial inflow on vortex intensification and its application to wind vortex generators

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Ide, Hiroshi
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Aerospace Engineering

The Department of Aerospace Engineering seeks to instruct the design, analysis, testing, and operation of vehicles which operate in air, water, or space, including studies of aerodynamics, structure mechanics, propulsion, and the like.

The Department of Aerospace Engineering was organized as the Department of Aeronautical Engineering in 1942. Its name was changed to the Department of Aerospace Engineering in 1961. In 1990, the department absorbed the Department of Engineering Science and Mechanics and became the Department of Aerospace Engineering and Engineering Mechanics. In 2003 the name was changed back to the Department of Aerospace Engineering.

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  • Department of Aerospace Engineering and Engineering Mechanics (1990-2003)

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A new wind vortex turbine, called "tornado-type wind generator system," was studied both theoretically and experimentally for the purpose of better understanding the basic nature of a vortex flow and further improvement of its power efficiencies. Analytical solutions were obtained from the Navier-Stokes equations for the velocity distributions along the radial distance. The result demonstrates the important nature of a vortex structure that, in order to intensify a vortex inside the tower, radial inflow must be provided from the side walls. Based upon this concept, the essential contribution of our experimental work was to furnish the radial inflow by utilizing the dynamic head of incoming wind;One circular model of 0.36 m(14") diameter with 0.58 m(23") height and two spiral models of 0.36 m inner diameter with 0.36 m height and 0.48 m(19") inner diameter with 0.58 m height were tested in a newly constructed wind tunnel of 1.22 x 1.22 m(4' x 4') at wind speeds from 2.54 m/s (5.68 mph) to 6.1 m/s(13.65 mph). It was found that for intensifying a vortex in such a tower it is more important to require the radial inflow in the boundary layer region rather than across the entire height of the tower. The maximum power efficiency, C(,p), obtained for the circular model with the radial inflow supply was about 3.8, which is about one order higher than that of conventional wind mills. This C(,p) was increased more than 100% in some cases as compared to that without the radial inflow supply. The maximum C(,p) for the large spiral model with the radial inflow supply was the highest, a value of 9, which is 22.5 times that of conventional windmills. This C(,p) was increased only about 15-30% as compared to that without the radial inflow supply because the spiral model produces the radial inflow by itself due to the decreasing radius of the spiral curvature. Static pressure measurements in the vortex core of the large spiral model showed that the maximum static pressure drop at the vortex center was more than 10 times the dynamic head of the wind with the radial inflow supply. The radial inflow lowered the pressure in the vortex core, a consequence of vortex intensification;In conclusion, extracting wind energy by creating and maintaining an extremely low pressure region of an intensified vortex at the turbine exit through viscous pumping is an improvement for wind machines in the aspect of C(,p) and consequently is a cost effective procedure.

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Fri Jan 01 00:00:00 UTC 1982