Theoretical comparison of non-axisymmetric air injection control of rotating stall on axial flow compressors

Nonaxisymmetric air injection control of stall is studied. Three existing control algorithms found in literature are modeled and analyzed. A three-state model is obtained for each algorithm. For two cases, conditions for linear stability and bifurcation criticality on control of rotating stall are derived and expressed in terms of implementation-oriented variables such as number of injectors. For the third case, bifurcation criticality conditions are not obtained due to complexity, though linear stability property is derived. A theoretical comparison between the three algorithms is made via the use of low-order models to investigate pros and cons of the algorithms in the context of operability.