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On the vortex created by multiple blades joined at a hub

Published online by Cambridge University Press:  03 February 2016

P. R. Spalart
P. R. Spalart*
Affiliation:
Boeing Commercial Airplanes, Seattle, USA
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Abstract

Experimental studies often use several blades, joined on the centreline, to generate a vortex in a wind tunnel. The circulation profile of this vortex is non-trivial, and a rapid prediction method will facilitate the design of such devices. Prompted by an experiment of Beninati and Marshall, such a model was derived. It assumes a large number of narrow blades and small turning angles, and rests on a balance of angular momentum and on simple aerofoil function. It is claimed to be valid even close to the centreline, can be completed analytically, contains no adjustable constants, and agrees well with two experiments although the turning angle reached 16° and the devices only had two or four blades. With typical geometries, the interference between blades makes the circulation profile quite different from that behind an elliptically-loaded wing, prompting some doubt over the relevance of such a vortex to those trailing real wings.

Type
Research Article
Information
The Aeronautical Journal , Volume 110 , Issue 1104 , February 2006 , pp. 117 - 119
Copyright
Copyright © Royal Aeronautical Society 2006 

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