Mitigation of transonic shock buffet on a supercritical airfoil through wavy leading edges
Mitigation of transonic shock buffet on a supercritical airfoil through wavy leading edges
Mitigation of the shock buffet phenomenon over a supercritical airfoil by means of wavy leading edges (WLEs) is analyzed with implicit large eddy simulations. A Dassault Aviation's V2C airfoil is simulated in a transonic flow with R e ∞ = 5.0 × 10 5 and M ∞ = 0.7 at α = 7.0 °. This airfoil profile is designed for transonic flows, delaying the onset of wave drag and decreasing the skin friction drag. The results of this upstream flow condition on a straight airfoil are a large oscillation of lift and drag coefficients. In the first part, time-averaged aerodynamic characteristics over a straight leading edge (SLE) airfoil and three modified airfoils with different wavy amplitudes are compared. The results show that overall WLE airfoils are more efficient than SLE ones, and the airfoil with the lowest amplitude (h = 0.0075) is the most efficient, increasing the lift coefficient and decreasing the drag coefficient. Flow unsteadiness plays a key role for airfoils in transonic flows at moderate and high angles of attack. Hence, the second part of the paper is a detailed unsteady analysis of flow phenomena. The starting point is an investigation of unsteady aerodynamic performance. It is observed that WLE airfoils are capable of significantly decreasing low-frequency oscillations' amplitude, identified with shock buffet. The best performance is obtained with h = 0.0125 where a high-frequency oscillation becomes the dominant unsteady phenomenon. High-frequency oscillations are identified through the application of a frequency filtering method to the flow field. It is proved that the oscillation on the SLE airfoil is related to vortex shedding, while the one on WLE airfoils is related to laminar separation bubble (LSB) breathing. Overall, the unsteady analysis shows a connection between shock buffet and LSB breathing phenomena on wavy airfoils and identifies the WLE amplitude as a key parameter to control this relation and mitigate the shock buffet.
026104-1-026104-16
Degregori, Enrico
a5df8cf9-3fcb-4290-9563-7c8b042c9819
Kim, Jae
fedabfc6-312c-40fd-b0c1-7b4a3ca80987
26 February 2021
Degregori, Enrico
a5df8cf9-3fcb-4290-9563-7c8b042c9819
Kim, Jae
fedabfc6-312c-40fd-b0c1-7b4a3ca80987
Degregori, Enrico and Kim, Jae
(2021)
Mitigation of transonic shock buffet on a supercritical airfoil through wavy leading edges.
Physics of Fluids, 33 (2), , [0036821].
(doi:10.1063/5.0036821).
Abstract
Mitigation of the shock buffet phenomenon over a supercritical airfoil by means of wavy leading edges (WLEs) is analyzed with implicit large eddy simulations. A Dassault Aviation's V2C airfoil is simulated in a transonic flow with R e ∞ = 5.0 × 10 5 and M ∞ = 0.7 at α = 7.0 °. This airfoil profile is designed for transonic flows, delaying the onset of wave drag and decreasing the skin friction drag. The results of this upstream flow condition on a straight airfoil are a large oscillation of lift and drag coefficients. In the first part, time-averaged aerodynamic characteristics over a straight leading edge (SLE) airfoil and three modified airfoils with different wavy amplitudes are compared. The results show that overall WLE airfoils are more efficient than SLE ones, and the airfoil with the lowest amplitude (h = 0.0075) is the most efficient, increasing the lift coefficient and decreasing the drag coefficient. Flow unsteadiness plays a key role for airfoils in transonic flows at moderate and high angles of attack. Hence, the second part of the paper is a detailed unsteady analysis of flow phenomena. The starting point is an investigation of unsteady aerodynamic performance. It is observed that WLE airfoils are capable of significantly decreasing low-frequency oscillations' amplitude, identified with shock buffet. The best performance is obtained with h = 0.0125 where a high-frequency oscillation becomes the dominant unsteady phenomenon. High-frequency oscillations are identified through the application of a frequency filtering method to the flow field. It is proved that the oscillation on the SLE airfoil is related to vortex shedding, while the one on WLE airfoils is related to laminar separation bubble (LSB) breathing. Overall, the unsteady analysis shows a connection between shock buffet and LSB breathing phenomena on wavy airfoils and identifies the WLE amplitude as a key parameter to control this relation and mitigate the shock buffet.
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Accepted/In Press date: 13 January 2021
Published date: 26 February 2021
Additional Information:
Funding Information:
The authors gratefully acknowledge the support of EPSRC (Engineering and Physical Sciences Research Council) for the present work under the CDT (Centre for Doctoral Training) in NGCM (Next Generation Computational Modelling) at the University of Southampton. We also acknowledge the high-performance computing facilities and services of the UK National Supercomputer ARCHER and the local IRIDIS5 at the University of Southampton in the completion of this work. We finally acknowledge the Dassault Systèmes for providing the V2C supercritical profile.
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© 2021 Author(s).
Identifiers
Local EPrints ID: 446618
URI: http://eprints.soton.ac.uk/id/eprint/446618
ISSN: 1070-6631
PURE UUID: 6ec40db6-e169-4e88-98df-90ced96183b9
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Date deposited: 16 Feb 2021 17:32
Last modified: 17 Mar 2024 03:00
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Author:
Enrico Degregori
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