Aeromechanical Control of High Speed Axial Compressor Stall and Engine Performance— Part I: Control Theoretic Models

Abstract

General methodologies are proposed in this twopart paper that further phenomenological understanding of compressible stall inception and aeromechanical control of highspeed axial compressors and engine performance. Developed in Part I are strategies for passive stabilization of compressible rotating stall, using tailored structural design and aeromechanical feedback control, implemented in certain classes of highspeed axial compressors used in research laboratories and by industry. Fundamentals of the stability of various dynamicallycompensated, highspeed compressors was set down from linearized, compressible structuralhydrodynamic equations of modal stall inception extended further in this study from previous work. A dimensionless framework for performancebased design of aeromechanicallycontrolled compression system stall mitigation and engine performance is established, linking specified design flow and worktransfer (pressure) operability to model stages or local blade components, velocity triangle environment, optimum efficiency, extended stall margin and operability loci, and aeromechanical detailed design. A systematic evaluation was made in Part II (Coleman and McGee, 2013, “Aeromechanical Control of HighSpeed Axial Compressor Stall and Engine Performance—Part II: Assessments of Methodology,â€‌ ASME J. Fluids Eng. (to be published)) on the performance of ten aeromechanical feedback controller schemes to increase the predicted range of stable operation of two laboratory compressor characteristics assumed, using static pressure sensing and local structural actuation to rudimentary postpone highspeed modal stall inception. The maximum flow operating range for each of the ten dynamicallycompensated, highspeed compression systems was determined using optimized or “tailoredâ€‌ structural controllers, and the results described in Part II of the companion paper are compared to maximum operating ranges achieved in corresponding lowspeed compression systems.