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Rotating stall and surge: alternate modeling and control concepts

Describes alternative formulations of the rotating stall control problem in axial compressors. Jet injection instead of bleed valve actuation is introduced, and asymmetric instead of 1D (plenum bleed) control of rotating stall waves is cast into the Galerkin framework, resulting in 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 (2D) 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.