Robust feedback control of flow-induced structural radiation of sound

Presented in this paper is the robust multivariable control of noise radiation from panels driven by turbulent flow. The controlled inputs are point forces to the panel and the feedback signals are panel accelerations. Collocated actuator/sensor locations on the panel are chosen such that vibration control will lead to a reduction in the radiated sound pressure levels. The multivariable controller is realized though a sequential loop closure approach. Each controller is designed in the frequency domain where the impact of system uncertainty and closed-loop sensitivity can be analyzed. The proposed frequency domain approach will also facilitate the design of feedback controllers that employ the natural dynamics of the panel for noise control purposes. The proposed design technique is experimentally validated on a panel subjected to turbulent flow in a quiet wind tunnel. Active control of the sound radiation was achieved at frequencies as high as 1000 Hz. Sound pressure level reductions of as much as 15 dB were achieved at the resonant frequencies of the panel modes. Overall reductions over the 100-1000 Hz band were approximately 5 dB.