Multivariable closed-loop control of the reattachment length downstream of a backward-facing step

Abstract

Active control of separated flows has become a major challenge in recent years. Whereas most of the work published so far is based on simulation studies this paper gives an example of a successful application of a multivariable closedloop flow control in wind tunnel experiments. A robust H ∞-controller is used to control the spanwise reattachment length downstream of a benchmark problem, a so-called backward-facing step. The synthesis of the controller is based on a family of identified linear black-box models. To reduce the conservatism of this approach, a nonlinear static precompensation is included. Tracking performance and disturbance rejection of the controller are tested in wind tunnel experiments. Copyright © 2005 IFAC.