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 [1,2] 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.

High-Reynolds-number wind turbine blade equipped with root spoilers – Part 1: Unsteady aerodynamic analysis using URANS simulations

“…The flow behind two well-known AAO devices, the vortex generators (VGs) and the Gurney flaps (GFs), has been largely investigated in order to understand its mechanism and control benefit, which is summarised hereafter. VGs are small fins (thin plates of usually triangular or rectangular shapes attached to a base plate) attached on the aerofoil suction side to delay stall by re-energising the boundary layer (see Taylor, 1947;Godard and Stanislas, 2006;Cathalifaud et al, 2009;De Tavernier et al, 2021;Gao et al, 2014;Lin, 2002;Skrzypiński et al, 2014;Perivolaris and Voutsinas, 2001). The vortices, aligned with the inflow leaving the device, increase the mixing between high speed flow (free stream) and low speed flow (boundary layer), thus delaying the flow separation (see Schubauer and Spangenberg, 1960).…”

High Reynolds number wind turbine blade equipped with root spoilers. Part I: Unsteady aerodynamic analysis using URANS simulations

“…re-energising the boundary layer (see Taylor et al (1947); Godard and Stanislas (2006); Cathalifaud et al (2009);De Tavernier et al (2021); Gao et al (2014); Lin (2002); Skrzypiński et al (2014); Perivolaris and Voutsinas (2001)). The vortices, aligned with the inflow leaving the device, increase the mixing between high speed flow (free stream) and low speed flow (boundary layer) thus delaying the flow separation (see Schubauer and Spangenberg (1960)).…”