Large field SPIV with separated sheets in a spanwise plane of a turbulent boundary layer with vortex generators

The Stereoscopic PIV is nowadays a well established measurement technique for turbulent flows. However, the accuracy and the spatial resolution are still highly questionable in presence of complex flow with both strong gradients and out of plane motions. To give guidelines for both setup and measurements of such flow configurations, a large region of overlap between two SPIV systems on the same laser light sheet is acquired in a plane normal to the streamwise direction of a high Reynolds turbulent boundary layer flow. A simple separation of the two light sheets is used to improve the accuracy of measurements by increasing the velocity dynamic range especially. It also presents the enhancement of accuracy due to the light sheets separation for characterizing streamwise vortices (i.e. perpendicular to the sheet). The present experiment was performed in the Laboratoire de Mécanique de Lille wind tunnel facility which has been specially designed to study fully developed turbulent boundary layer at high Reynolds number. The outlooks are to study in detail the physics of the streamwise vortices generated from vortex generators taking advantage of large scales of this turbulent boundary layer.