ROBUST FEEDBACK-CONTROL OF FLOW-INDUCED STRUCTURAL RADIATION OF SOUND

A significant amount of the interior noise of aircraft and automobiles is a result of turbulent boundary layer excitation of the vehicular s tructure. In this investigation, the feasibility of active robust feed back control of the noise due to this type of excitation is studied. T he structural sound radiation system investigated is comprised of a si mply supported panel excited by turbulent flow. An analytical model of this system is developed to evaluate the robust feedback control syst em design strategy. The model consists of a modal description of the e xcitation of the plate by a turbulent boundary layer, a modal represen tation of the plate vibrations, and an acoustic model of the sound rad iated from the plate. Parametric uncertainties of 1% variation in the natural frequencies and 5% variation in the damping ratio are consider ed. A frequency domain controller design approach is utilized to devel op a robust controller. Performance objectives are specified which inc lude output performance of the sound radiated by the plate and control effort constraints on the force applied to the plate by the controlle r. Plate acceleration feedback is used in an effort to reduce the soun d-pressure level. Approximately 16 and 8 dB of sound-pressure level re duction were achieved at the first and third resonances, respectively. (C) 1997 Acoustical Society of America.