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Artikel

Advanced Fluid Research On Drag reduction in Turbulence Experiments - AFRODITE-

Författare: Fransson, J. H. M.
Dokumenttyp: Konferens
Tillstånd: Publicerad
Tidskrift: Svenska mekanikdagarna, Göteborg, June 13-15 2011
Volym: 1   75
År: 2011

Abstract

A hot topic in today's debate on global warming is drag reduction in aeronautics. The most beneficial concept for drag reduction is to maintain 2the major portion of the airfoil laminar. Estimations show that the potential drag reduction can be as much as 15%, which would give a significant reduction of NOx and CO emissions in the atmosphere considering that the number of aircraft take offs, only in the EU, is over 19 million per year. An important element for successful flow control, which can lead to a reduced aerodynamic drag, is enhanced physical understanding of the transition to turbulence process. In previous tuned wind tunnel measurements it has been shown that roughness elements can be used to sensibly delay transition to turbulence. The result is revolutionary, since the common belief has been that surface roughness causes earlier transition and in turn increases the drag, and is a proof of concept of the passive control method per se. The beauty with a passive control technique is that no external energy has to be added to the flow system in order to perform the control, instead one uses the existing energy in the flow. Within the research programme -AFRODITE- we will take this passive control method to the next level by making it twofold, more persistent and more robust. Transition prevention is the goal rather than transition delay and the method will be extended to simultaneously control separation, which is another unwanted flow phenomenon especially during airplane take offs. AFRODITE will be a catalyst for innovative research, which will lead to a cleaner sky.