VIBROACOUSTIC MODELING OF A LAUNCH VEHICLE PAYLOAD FAIRING FOR ACTIVE ACOUSTIC CONTROL

Low frequency active acoustic attenuation is examined for the payload fairing of a representative small launch vehicle. The feasibility of using structural sensors and actuators for active acoustic control is assessed with a numerical model of the fairing. The results of the numerical analysis indicate that broadband damping decreases the interior overall sound pressure level between 4 dB and 10 dB, depending on the amount of structural damping that is added to the vibration modes. Singular value analyses demonstrate that point force actuators and in-plane strain actuators have the control authority for active acoustic control. Control studies indicate that local velocity feedback reduces the average vibration level of the fairing by roughly 50%, and that the force levels required of the control system are within the range of conventional point force and piezoceramic actuators.