ACTIVE CONTROL OF CASCADE FLUTTER BY MEANS OF SOUND-WAVES FROM DUCT WALL SOURCES

A theoretical analysis of the cascade flutter suppression using active acoustic excitations is presented. A model considered herein is a thr ee-dimensional linear cascade of flat plates oscillating in a subsonic flow between parallel walls. One of the walls is partially made of ac tuator surface like a loudspeaker which generates sound waves with the same frequency as that of the blade oscillation. The unsteady aerodyn amic work on blades due to oscillation and interaction with the acoust ic disturbances generated from the actuator surface is calculated. Dep endence of the aerodynamic work on the location, width, vibration mode s of the actuator surface and the phase difference between the cascade and actuator surface oscillations are investigated. Numerical results show the optimum conditions of the actuator surface oscillation for e ffective flutter suppression.