Title: Transition control by micron-sized roughness elements: stability analyses and wind tunnel experiments

Authors: Olivier Vermeersch; Daniel Arnal; Itham Salah El Din

Addresses: Aerodynamics and Energetics Models Department, ONERA, The French Aerospace Lab, Centre de Toulouse, 2 Avenue Edouard Belin, 31055 Toulouse, Cedex 4, France ' Aerodynamics and Energetics Models Department, ONERA, The French Aerospace Lab, Centre de Toulouse, 2 Avenue Edouard Belin, 31055 Toulouse, Cedex 4, France ' Applied Aerodynamics Department, ONERA, The French Aerospace Lab, Centre de Meudon, 8 rue des Vertugadins, 92190 Meudon, France

Abstract: This paper presents an experimental study of cross-flow transition control on a swept wing by micron-sized roughness elements. The process consists in using an array of micron-sized roughness elements placed close to the leading edge to damp the amplitude of cross-flow instabilities and thus delay the laminar to turbulent transition. This phenomenon is studied on the pressure side of the DTP-B model placed in the Onera Fauga-Mauzac F2 wind tunnel. The sweep angle was fixed at Φ = 40° for different angles of attack AoA = 5, 6, 7° and a velocity range varying between 60 and 90 (m/s). The influence of several geometrical parameters, such as the spacing and height of control devices, on transition delay has been investigated. Total pressure probing has been used in order to characterise the wavelength of natural (without control) cross-flow instabilities but also the one of disturbances generated by roughness elements. Both naphthalene visualisations and infra-red imaging have been used to locate the transition.

Keywords: boundary layers; laminar turbulent transition; nonlinear stability theory; cross-flow instability; transition control; roughness elements; stability analysis; wind tunnel experiments; swept wings; angles of attack; velocity.

DOI: 10.1504/IJESMS.2013.052381

International Journal of Engineering Systems Modelling and Simulation, 2013 Vol.5 No.1/2/3, pp.84 - 98

Available online: 21 Feb 2013 *

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