Active Control of Supersonic Cascade Flutter by Sound Waves from Actuator Surface.

Abstract

A theoretical analysis of cascade flutter suppression using an active acoustic excitation technique is conducted for supersonic cascades. A three-dimensional linear cascade of flat plates oscillating in a supersonic uniform flow between parallel walls is considered. One of the walls is partially composed of an actuator surface such as a loudspeaker which generates sound waves with the same frequency as that of the blade oscillation. The aerodynamic work on blades by unsteady fluid forces due to oscillation of blades themselves and interaction with the acoustic disturbances generated from the actuator surface is calculated. Dependences of the aerodynamic work on the location, width and vibration modes of actuator surface, and the phase difference between the cascade and actuator surface oscillations are investigated. It is revealed that the parametric dependences and the condition of the actuator surface motion for effective flutter suppression are very much different from those for subsonic cascades.