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Vortex force maps for three-dimensional unsteady flows with application to a delta wing
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Li, Juan, Zhao, Xiaowei and Graham, Michael (2020) Vortex force maps for three-dimensional unsteady flows with application to a delta wing. Journal of Fluid Mechanics, 900 . A36. doi:10.1017/jfm.2020.515 ISSN 0022-1120.
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Official URL: https://doi.org/10.1017/jfm.2020.515
Abstract
The unsteady forces acting on a body depend strongly on the local flow structures such as vortices. A quantitative understanding of the contribution of these structures to the instantaneous overall force is of fundamental significance. In the present study, a threedimensional (3-D) vortex force map (VFM) method, extended from a two-dimensional (2D) one, is used to provide better insight into the complex 3-D flow dynamics. The VFM vectors are obtained from solutions of potential equations and used to build the 3-D VFMs where the critical regions and directions associated with significant positive or negative contributions to the forces are identified. Using the existing velocity/vorticity field near the body, these VFMs can be used to obtain the body forces. A decomposed form of the force formula is also derived to separate the correction term contributed from the uncaptured vortices (close to or far away from the body). The present method is applied to the starting flow of a delta wing at high angle of attack, where leading edge vortices are enhanced and stabilized by an axial flow effect. The analogy between the normal force of a slender delta wing and that of a two dimensional flat plate with a steadily growing span is demonstrated via the VFM analysis. We find, for this application, that the force evolution exhibits some similar behavior to a two dimensional airfoil starting flow and, surprisingly, the force contribution mainly comes from the conical vortex sheet rather than the center core. Moreover, a quantitative understanding of the influence of leading edge vortices (LEVs) in different evolution regimes on the body force is demonstrated.
Item Type: | Journal Article | ||||||||
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Subjects: | T Technology > TL Motor vehicles. Aeronautics. Astronautics | ||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Engineering > Engineering | ||||||||
Library of Congress Subject Headings (LCSH): | Unsteady flow (Aerodynamics), Vortex-motion, Airplanes -- Wings, Triangular | ||||||||
Journal or Publication Title: | Journal of Fluid Mechanics | ||||||||
Publisher: | Cambridge University Press | ||||||||
ISSN: | 0022-1120 | ||||||||
Official Date: | 10 October 2020 | ||||||||
Dates: |
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Volume: | 900 | ||||||||
Article Number: | A36 | ||||||||
DOI: | 10.1017/jfm.2020.515 | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Reuse Statement (publisher, data, author rights): | This article has been published in a revised form in Journal of Fluid Mechanics [http://doi.org/10.1017/jfm.2020.515. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. © copyright holder. | ||||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||||
Copyright Holders: | © The Author(s), 2020. Published by Cambridge University Press | ||||||||
Date of first compliant deposit: | 23 July 2020 | ||||||||
Date of first compliant Open Access: | 13 February 2021 | ||||||||
RIOXX Funder/Project Grant: |
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