22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-3.4.2

EFFECT OF SOUND ON LAMINAR TURBULENT TRANSITION ON SWEPT WINGS

S. Aubrun, A. Seraudie, D. Biron, D. Arnal
ONERA, 2 avenue Edouard Belin, Toulouse, France

Keywords: swept wing, transition, receptivity, sound, hot film and hot wire anemometry

The effect of sound on laminar-turbulent transition process is studied for 3D boundary layers governed by streamwise or crossflow instabilities. We quantify the shift upstream of the transition location versus sound level in both cases. We show that the effect of sound is characterized by a shortening of the transition length. Then, the comparison between linear stability theory results and experiments enables us to show that the excitation modify the initial amplitude of instabilities but not their amplification factor. Finally, we propose a relationship between the loss of N factor and sound level which is valid for streamwise or crossflow cases.

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