Global stability analysis - a key enabler in reduced order models and flow control

¹ Pozna‚ University of Technology n Institute of Combustion Engines and Transportation Poland
² Institut Pprime, CNRS - Université de Poitiers - ENSMA Département Fluides, Thermique, Combustion, CEAT Poitiers, France
³ Department of Electrical and Computer Engineering Northeastern University Boston, USA

Abstract

In the current study, Reduced Order Models (ROMs) targeting strategies for experimental feedback flow control are discussed. For practical reasons, such models should incorporate a range of flow operating conditions with a small number of degrees of freedom. Standard POD Galerkin models are challenged by overoptimization at one operating condition [1]. The extension of dynamic range with additional global flow stability modes is the first applied technique. Further side constraints for control-oriented ROMs are taken into account by a “least-dimensional” Galerkin approximation based on a novel technique for continuous mode interpolation [2]. This interpolation preserves the model dimension of a single state while covering several states by adjusting (interpolated) modes. The resulting three-dimensional (3D) Galerkin model is presented for the transient flow around NACA-0012 airfoil and shown to be in a good agreement with the corresponding direct numerical simulation (DNS).