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Laminar post-stall wakes of tapered swept wings

Published online by Cambridge University Press:  24 November 2023

Jean Hélder Marques Ribeiro Open the ORCID record for Jean Hélder Marques Ribeiro [Opens in a new window] ,
Jacob Neal ,
Anton Burtsev Open the ORCID record for Anton Burtsev [Opens in a new window] ,
Michael Amitay Open the ORCID record for Michael Amitay [Opens in a new window] ,
Vassilios Theofilis Open the ORCID record for Vassilios Theofilis [Opens in a new window]  and
Kunihiko Taira Open the ORCID record for Kunihiko Taira [Opens in a new window]
Jean Hélder Marques Ribeiro*
Affiliation:
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, USA
Jacob Neal
Affiliation:
Department of Mechanical, Aeronautical, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
Anton Burtsev
Affiliation:
Department of Mechanical and Aerospace Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, UK
Michael Amitay
Affiliation:
Department of Mechanical, Aeronautical, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
Vassilios Theofilis
Affiliation:
Department of Mechanical and Aerospace Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, UK
Kunihiko Taira
Affiliation:
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, USA
*
Email address for correspondence: jeanmarques@g.ucla.edu
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Abstract

While tapered swept wings are widely used, the influence of taper on their post-stall wake characteristics remains largely unexplored. To address this issue, we conduct an extensive study using direct numerical simulations to characterize the wing taper and sweep effects on laminar separated wakes. We analyse flows behind NACA 0015 cross-sectional profile wings at post-stall angles of attack $\alpha =14^\circ$–$22^\circ$ with taper ratios $\lambda =0.27$–$1$, leading-edge sweep angles $0^\circ$–$50^\circ$ and semi aspect ratios $sAR =1$ and $2$ at a mean-chord-based Reynolds number of $600$. Tapered wings have smaller tip chord length, which generates a weaker tip vortex, and attenuates inboard downwash. This results in the development of unsteadiness over a large portion of the wingspan at high angles of attack. For tapered wings with backward-swept leading edges, unsteadiness emerges near the wing tip. On the other hand, wings with forward-swept trailing edges are shown to concentrate wake-shedding structures near the wing root. For highly swept untapered wings, the wake is steady, while unsteady shedding vortices appear near the tip for tapered wings with high leading-edge sweep angles. For such wings, larger wake oscillations emerge near the root as the taper ratio decreases. While the combination of taper and sweep increases flow unsteadiness, we find that tapered swept wings have more enhanced aerodynamic performance than untapered and unswept wings, exhibiting higher time-averaged lift and lift-to-drag ratio. The current findings shed light on the fundamental aspects of flow separation over tapered wings in the absence of turbulent flow effects.

JFM classification

Vortex Flows: Vortex dynamics Wakes/Jets: Wakes Wakes/Jets: Separated flows
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 976 , 10 December 2023 , A6
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Copyright
© The Author(s), 2023. Published by Cambridge University Press

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Footnotes

†

Present address: Faculdade de Engenharia Mecânica, Universidade Estadual de Campinas, Campinas, SP 13083-860, Brazil.

‡

Present address: Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, TX 78712, USA.

§

Present address: Faculty of Aerospace Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.

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