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Autorotation of an elliptic cylinder about an axis perpendicular to the flow

Published online by Cambridge University Press:  19 April 2006

Hans J. Lugt
Hans J. Lugt
Affiliation:
David W. Taylor Naval Ship Research and Development Center, Bethesda, Maryland 20084, U.S.A.
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Abstract

Autorotation of an elliptic cylinder about an axis fixed perpendicular to a parallel flow is explained in this paper by means of numerical solutions of the Navier-Stokes equations. Potential-flow theory predicts, for constant angular velocity, half a period in which a torque supports rotation and half a period in which it opposes rotation, with vanishing torque in the average. This balance is disturbed by viscous-flow effects in such a way that, for a given angular velocity, vortex shedding either damps rotation or, under certain conditions, favours rotation. The proper interplay of those conditions, which include synchronization of vortex shedding and rate of rotation, results in auto-rotation. The numerical results for Re [les ] 400 are compared with experimental data for Re = 90000 from the literature. The agreement of the force coefficients and the large-scale flow patterns is surprisingly good.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 99 , Issue 4 , 29 August 1980 , pp. 817 - 840
Copyright
© 1980 Cambridge University Press

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