Effect of Acoustic Control on the Flutter Boundaries of Supersonic Cascade

Abstract

The active acoustic control of the supersonic cascade flutter under steady loading is studied. A three-dimensional linear cascade of blades oscillating in a supersonic flow between parallel walls is considered. The effect of steady loading, i.e., angle of attack, camber and thickness on the unsteady aerodynamic force is dealt with on the basis of the double linearization theory. One of the walls is partially made of actuator surface like a loudspeaker which generates sound waves at the same frequency as that of the blade oscillation, so that the unsteady aerodynamic force due to acoustic disturbances generated from the actuator surface cancels the existing unsteady force on the blades due to blade motions themselves. The optimum condition of the actuator surface geometry and motion is investigated and the capability to enlarge the flutter free domain is demonstrated.