Energy efficiency and performance limitations of linear adaptive control for transition delay

Författare: Fabbiane, N., Bagheri, S., Henningson, D.S.H.
Dokumenttyp: Artikel
Tillstånd: Inskickad
Tidskrift: Journal of Fluid Mechanics


Reactive-control techniques have been longly investigated to control local flow instabilities in boundary-layer flows – Tollmien-Schlichting waves – that would eventually cause laminar-to-turbulence transition. Several studies have been published about the control of two-dimensional (2D) disturbances supposing a transition delay. In this study, a three-dimensional (3D) disturbance environment is considered in a 2D zero-pressure-gradient boundary-layer flow. A control- law based on a multi-input-multi-output (MIMO) filtered-x least-mean-squares (fxLMS) adaptive algorithm is introduced and its performances are analysed for increasing disturbance amplitude. Transition delay is achieved by the investigated control set-up; moreover, an energy budget is conducted in order to asses the net energy saving capabilities of the investigated control approach. Ideal as well as real actuators models are considered, focusing in particular on dielectric-barrier-discharge (DBD) plasma actuators. To our knowledge, this is the first time that drag-reduction and energy-saving capabilities are studied for reactive transition-delay techniques.