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

Experimental analysis of transition delay by means of roughness elements / J.H.M. Fransson; A. Talamelli; L. Brandt; C. Cossu. - ELETTRONICO. - 11:(2006). (Intervento presentato al convegno 36th AIAA (American institute of Aeronautics and Astronautics) Fluid Dynamics Conference tenutosi a San Francisco nel 5-8 Giugno 2006).

Experimental analysis of transition delay by means of roughness elements

TALAMELLI, ALESSANDRO;
2006

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
2006
2006 AIAA Meeting Papers
Experimental analysis of transition delay by means of roughness elements / J.H.M. Fransson; A. Talamelli; L. Brandt; C. Cossu. - ELETTRONICO. - 11:(2006). (Intervento presentato al convegno 36th AIAA (American institute of Aeronautics and Astronautics) Fluid Dynamics Conference tenutosi a San Francisco nel 5-8 Giugno 2006).
J.H.M. Fransson; A. Talamelli; L. Brandt; C. Cossu
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/28705
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