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Conference Papers Year : 2006

Experimental analysis of transition delay by means of roughness elements

Abstract

An experimental activity aimed at the development of a passive method for viscous drag reduction in an aerodynamic body is presented. The reduction is achieved by delaying the laminar-turbulent transition of the boundary layer. The research is motivated by previous linear stability analysis where it was demonstrated that stable streaks in a boundary layer are capable to stabilize the growth of Tollmien-Schlichting waves. In this paper the results of a series of experiments on a flat plate are presented. Firstly, it is 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. Secondly, it is demonstrated that the generated streaks are really effective in reducing the growth of the Tollmien-Schlichting waves as predicted by the theory. Finally, it is shown that using this passive control technique it is possible to sensibly delay transition to turbulence.
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Dates and versions

hal-01026021 , version 1 (21-07-2014)

Identifiers

  • HAL Id : hal-01026021 , version 1

Cite

J.H.M. Fransson, A. Talamelli, L. Brandt, Carlo Cossu. Experimental analysis of transition delay by means of roughness elements. 36th AIAA Fluid Dynamics Conference, Jun 2006, San Francisco, United States. pp.1464-1478. ⟨hal-01026021⟩
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