Time-resolved tomographic PIV investigation of turbulent flow control by vortex generators on a backward-facing step

Kurzfassung

An experimental study is presented for turbulent flow control in backward-facing step (BFS) flow by time-resolved tomographic particle image velocimetry (TR tomo-PIV) and high-resolution 2D-2C- PIV. Vortex generators were designed and implemented on a BFS with a zero pressure gradient. As passive flow control devices, the vortex generators were wedge-shaped, backward oriented, and transversely mounted upstream of the step. The experiments were carried out in the 1-m low speed wind tunnel at DLR in Göttingen, Germany. The Reynolds number was Reh = 2.0×10^4, based on the free stream velocity U∞ = 10 m/s and the step height h = 30 mm. TR tomo-PIV was employed to measure the separated shear layer flow within a measurement volume of 50×60×10 mm^3 in x-, y- and z-direction respectively, which located right behind the step and above the plate. Four high-speed CMOS cameras were mounted under the glass plate in a pyramidal arrangement and recorded image pairs up to 1 kHz. The measurement volume was illuminated by transverse laser light beam which was reflected back and forth between two mirrors on both sides of the flow to increase the light intensity.