Analysis and comparison of transonic buffet phenomenon over several 3D wings
Résumé
The transonic buffet is a complex aerodynamic instability which appears on wings and airfoils at high subsonic Mach number and/or angle of attack. It consists in a shock oscillation that implies pressure and notably lift fluctuations, thus limiting the flight envelope of civil aircrafts. The aim of the present paper is to improve the understanding of the flow physics of the 3D transonic buffet over swept wings through the analysis and comparison of four different experimental databases, and in particular identifying characteristic values of the buffet phenomenon such as Strouhal numbers, convection velocities, buffet onset etc. It is shown that some non-dimensionalized numbers are kept constant between the different databases and consequently can be considered as characteristics of the 3D buffet, whereas others change. The key to understanding the transonic buffet phenomenon lies in explaining the common features but also the variability of transonic buffet parameters in different configurations. In particular, it is shown that the 3D buffet is characterized by a Strouhal number in the range .2-0.3 and a spanwise convection velocity of 0.245 +- 0.015Uinfini, where Uinfini denotes the freestream velocity. These characteristic ranges of values are much larger those of the 2D buffet phenomenon, which suggests different physical mechanisms.
Origine : Fichiers produits par l'(les) auteur(s)
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