Controller Complexity for Active Control of Turbulent Boundary-Layer Noise from Panels

Abstract

An experimental study of feedback controller complexity vs noise reduction performance for active structural acoustic control of turbulent-boundary-layer (TBL)-induced sound radiation from a panel is described. The reduction of total radiated sound power as a function of the number of actuators, sensors, and controller cost function on a mock aircraft sidewall subjected to TBL excitation are discussed. The results demonstrate total radiated sound power reductions of 15 dB at resonances and 10 dB integrated over 150-1000 Hz for a three-actuator and 15-sensor case. The controller configuration was then simplified to one actuator and four sensors (summed outputs) and was found to produce 10-15-dB reductions in sound power at resonances and 9 dB integrated over the control bandwidth. This result demonstrates the potential for achieving significant reductions in radiated sound power with a relatively simple actuator/sensor topology.