Direct numerical simulations of transonic flow around an airfoil at moderate Reynolds numbers

Abstract

In order to reduce friction and wave drag on the wings of more efficient next generation aircraft, it is important to understand laminar-turbulent boundary-layer transition and shockwave interactions. In this contribution, fully-resolved direct numerical simulations of Dassault Aviation’s V2C profile at transonic conditions and a Reynolds number of half a million are presented. Kelvin-Helmholtz instabilities appear in the shear layers on the pressure- and
suction-sides, followed by a self-sustained laminar-turbulent transition process promoted by the stretching of rib vortices between larger co-rotating structures. Multiple acoustic structures interacting with the boundary layer are also observed, together with upstream-propagating shock waves. Regions of flow separation on the suction side exhibit unsteadiness with Strouhal numbers in the range of St 0:5 􀀀 0:6. This is distinct from a standing wave oscillation in liftat St = 0:12, which agrees well with transonic buffet frequencies, reported for experiments on the same airfoil at higher Reynolds numbers. The insensitivity of the principal results to the chosen grid resolution and spanwise domain size is carefully established.

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Identifiers

ORCID for Markus Zauner: orcid.org/0000-0002-6644-2990

ORCID for Neil Sandham: orcid.org/0000-0002-5107-0944

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