Aerodynamic force by Lamb vector integrals in unsteady compressible flows
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 25 January 2024
Abstract
Purpose
This study aims to propose an aerodynamic force decomposition which, for the first time, allows for thrust/drag bookkeeping in two-dimensional viscous and unsteady flows. Lamb vector-based far-field methods are used at the scope, and the paper starts with extending recent steady compressible formulas to the unsteady regime.
Design/methodology/approach
Exact vortical force formulas are derived considering inertial or non-inertial frames, viscous or inviscid flows, fixed or moving bodies. Numerical applications to a NACA0012 airfoil oscillating in pure plunging motion are illustrated, considering subsonic and transonic flow regimes. The total force accuracy and sensitivity to the control volume size is first analysed, then the axial force is decomposed and results are compared to the inviscid force (thrust) and to the steady force (drag).
Findings
Two total axial force decompositions in thrust and drag contributions are proposed, providing satisfactory results. An additional force decomposition is also formulated, which is independent of the arbitrary pole appearing in vortical formulas. Numerical inaccuracies encountered in inertial reference frames are eliminated, and the extended formulation also allows obtaining an accurate force prediction in presence of shock waves.
Originality/value
No thrust/drag bookkeeping methodology was actually available for oscillating airfoils in viscous and compressible flows.
Keywords
Acknowledgements
Erratum: It has come to the attention of the publisher that the article Minervino, M. and Tognaccini, R. (2024), “Aerodynamic force by Lamb vector integrals in unsteady compressible flows”, International Journal of Numerical Methods for Heat & Fluid Flow, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/HFF-06-2023-0350, contained text errors, which was introduced during the production process. M on pages 21 and 22 has been changed to M∞ and ∇μ in equations (20) and (27) has been changed to Fμ. The publisher sincerely apologises for these errors and for any confusion caused.
Citation
Minervino, M. and Tognaccini, R. (2024), "Aerodynamic force by Lamb vector integrals in unsteady compressible flows", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. ahead-of-print No. ahead-of-print. https://doi.org/10.1108/HFF-06-2023-0350
Publisher
:Emerald Publishing Limited
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