2014/05/16 by Thomas Duriez, Duriez, Thomas, Jean‐Luc Aider +5
Engineering · #Aerodynamics and Acoustics in Jet Flows #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Plasma and Flow Control in Aerodynamics
paper · pdf · doi:10.48550/arxiv.1405.4234
openalex publication_date 2014/05/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Many experimental and numerical studies report a large reduction of the recirculation bubble in Backward-Facing Step flows or airfoils in stall situation when excited at the natural shedding frequency f0. Through a simple experiment using Dielectric Barrier Discharge actuator, we find a different result. For a given Reynolds number, the frequency of the perturbation is varied for a fixed duty-cycle dc = 27%. Through phase-averaging of Particle Image Velocimetry measurements, we show that the actuation creates a forced vortex which interacts with the natural shedding with a different phase velocity than the unforced one. The largest reduction of the recirculation bubble (-35%) is obtained in a very narrow frequency range around 0.73 f0 where early vortex pairing occurs between forced and unforced vortices. Phase averaging shows that in this case, the actuation clearly forces the vortex pairing in the shear layer. On the contrary, when the forcing frequency is higher, the shear layer behaves like an amplifier synchronized on the forced frequency, leading to a constant 10% reduction of the recirculation bubble.