The flow structure behind vortex generators embedded in a decelerating turbulent boundary layer

Abstract

The objective of the present work is to analyse the behaviour of a turbulent decelerating boundary layer under the effect of both passive and active jets vortex generators (VGs). The stereo PIV database of Godard and Stanislas [1 Godard, G. and Stanislas, M. 2006. Control of a decelerating boundary layer. Part 1: Optimization of passive vortex generators. Aerosp. Sci. Technol., 10(3): 181–191. [Crossref], [Web of Science ®] , [Google Scholar],2 Godard, G. and Stanislas, M. 2006. Control of a decelerating boundary layer. Part 3: Optimization of round jets vortex generators. Aerosp. Sci. Technol., 10(6): 455–464. [Crossref], [Web of Science ®] , [Google Scholar]] obtained in an adverse pressure gradient boundary layer is used for this study. After presenting the effect on the mean velocity field and the turbulent kinetic energy, the line of analysis is extended with two points spatial correlations and vortex detection in instantaneous velocity fields. It is shown that the actuators concentrate the boundary layer turbulence in the region of upward motion of the flow, and segregate the near-wall streamwise vortices of the boundary layer based on their vorticity sign.