Trailing-edge dynamics and morphing of a deformable flat plate at high Reynolds number by time-resolved PIV

Abstract

The present paper investigates the turbulent wake structure in the near-region past the trailing edge of a deformable inclined plate. The plate is actuated by shape memory alloys. Using these actuators a significant deformation (bending) can be achieved (≈10% of the chord) under the aerodynamic loads corresponding to a Reynolds number of 200000. The shear-layer dynamics as well as the mean velocity and turbulent stresses have been quantified for a reference case (flat plate inclined at 10°). The present study investigates the modification of the shear-layer and near-wake dynamics achieved by means of the dynamic deformation of the plate compared with static cases that include three intermediate positions of the deformed plate. The comparison of the static cases with the dynamic regime discusses the validity of the quasi-static hypothesis for the present low frequency actuation. It is found that the present actuation enhances the shearing mechanisms past the trailing-edge and modifies the von-Kármán mode as well as the structure of the shear-layer, Kelvin–Helmholtz eddies. Moreover, the increase of the bending enhances the appearance of the pairing mechanism between successive shear-layer eddies and the interaction between the von-Kármán and shear-layer instability modes. Furthermore, it has been found that the increase of the plate׳s curvature leads to an attenuation of the shear-layer amplitude and of the overall spectral energy, concerning the most deformed position.