Active control of flutter in turbomachinery using off blade actuators sensors. Part II: Control algorithm

We describe control design for fan or compressor blades flutter in gas turbine engines. The experimental implementation of active flutter control on a sub-scale fan rig consisted of an array of audio speaker-powered volumetric sources connected to the flow path equally spaced along the circumference axially located between all experimental fan and its exit guide vanes (stator). Blade arrival time detectors based on eddy current sensors placed at the leading end of the blade-tip line were used to generate real-time blade deflection signals. An observer was used to reconstruct the flutter modes. A pole-placement controller was used to generate the speaker command signals.