High amplitude steady streaks in flat plate boundary layers

Authors: Talamelli, A., Fransson, J. H. M.
Document Type: Conference
Pubstate: Published
Journal: 40th AIAA Fluid Dynamics Conference and Exhibit. Chicago, Illinois, USA. 28 June - 1 July 2010
Volume: 15   1-14
Year: 2010


This experimental activity is part of large research program aimed at the development of a passive method for viscous drag reduction in aerodynamic bodies. The drag reduction, achieved by delaying the laminar-turbulent transition of the boundary layer, is obtained by generating in the boundary layer stable laminar streaks which are shown to stabilize the growth of Tollmien-Schlichting waves. A first series of experiments have shown that by means of suitable roughness elements it is possible to generate stable steady streaks of amplitudes up to 12% of the free stream velocity. In this paper we explore the possibility to generate streaks of much larger amplitude by using a row of Vortex Generators (VGs). Experiments have been performed showing that amplitudes up to 30% can be obtained without any secondary instability of the generated streaks can be observed. Finally, it is also demonstrated that the streaks can be reinforced by the presence of second array of vortex generators positioned downstream.