ADAPTIVE FEEDBACK CONTROL OF COMBUSTION INSTABILITY IN ANNULAR COMBUSTORS

An adaptive feedback control strategy for axisymmetric annular combustors is developed. The controller uses the pressure perturbation at a fixed axial location downstream of the flame-provided by multiple pressure measurements around the combustor circumference-as the control input. Control is achieved via modulation of the fuel flow rate at multiple fuel valve locations. The controller is implemented in a computational low-order thermoacoustic network model of an annular combustor. Time domain simulations show that the controller stabilizes both longitudinal and circumferential unstable modes (including the simultaneous control of multiple unstable modes), even from within the limit cycle. By changing the flame transfer function with time, it is shown that control is retained following a large change in the combustor operating conditions.