Shear Layer and Shedding Modes Excitations of a Backward-Facing Step Flow by Surface Plasma Discharge

QC 20200219
The present experimental study interests in determining the influence of a linear plasma actuator (dielectric barrier discharge) on the development of a separated turbulent shear layer. More specifically, the plasma actuator is used to impose periodic perturbations at the step corner of a backward-facing step. Two different modes of excitation are explored. One concerns the shear layer mode of instability, a mode whose amplification leads to a minimization of the recirculation bubble. The present investigation shows how a dielectric barrier discharge plasma actuator can impose periodic perturbations that excite the shear layer mode and result in a strong regularization of the vortex street. The case of excitation at the shedding mode is also experimentally investigated using a DBD actuator. The measurements show the increase in Reynolds stress caused by this excitation as well as the specific growing mechanism of the shear layer. Indeed, phase-averaged flow measurements highlights the difference in the mechanism of development of the shear layer regarding the type of excitation used, the shear layer mode promoting a growing mechanism by fluid entrainment while the shedding mode enhancing the pairing of successive vortical flow structures.

Sujar Garrido, PatriciaKTH,Strömningsmekanik och Teknisk Akustik,Linné Flow Center, FLOW(Swepub:kth)u1ipfepj (author)
Bonnet, J. -P (author)
Moreau, E. (author)
KTHStrömningsmekanik och Teknisk Akustik (creator_code:org_t)

In:Advances in Effective Flow Separation Control for Aircraft Drag ReductionCham : Springer, s. 55-74

By the author/editor: Benard, N.; Sujar Garrido, P ...; Bonnet, J. -P; Moreau, E.

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