Active control of structural-acoustic systems - Noise reduction in payload fairings
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© 1996, American Institute of Aeronautics and Astronautics, Inc. Active control of structural-acoustic systems using PZT stack actuators is presented using the coupled modes method. Noise reduction inside a 3.66 m x 3.66 m x 6.17 m cavity with a simply-supported endplate is treated as a precursor to the design of active control of launch vehicle composite-isogrid payload fairing acoustics. A comparison of the noise levels due to simulated lift-off conditions are presented for aluminum and composite endplates, with and without active control. The input pressure disturbance is of short duration and random (broad-band) in nature, with levels of 110-115 dB. The pressure inside the cavity is considerably higher at certain frequencies, reaching as high as 130 dB with the use of the composite endplate. A reduction in pressure levels of 15-25 dB is possible over a frequency range of 20-300 Hz with the use of PZT actuators, with reasonable limits on the applied voltage. The results of this preliminary study are highly encouraging for further research on the challenging problem of active broadband noise reduction inside composite-isogrid payload fairings.
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