Rotating stall and surge: Alternate modeling and control concepts

This paper describes alternative formulations of the rotating stall control problem. Jet injection instead of bleed valve actuation is introduced, and asymmetric instead of one-dimensional (plenum bleed) control of rotating stall waves is cast into the Galerkin framework, resulting iri a four-state nonlinear model. Shortcomings of very low-order modeling are discussed, and it is suggested that a more general high-order Galerkin model is more suitable for control law design. Two asymmetric (two-dimensional) nonlinear control examples are then given. The first demonstrates the utility of asymmetric feedback by showing how it can, unlike 1D control, alter the equilibrium properties of the low-order model. The second shows how a Lyapunov analysis motivates a family of nonlinear controllers which account for the multi-dimensional nature of the rotating stall stabilization problem.