NOISE CONTROL OF A PAYLOAD FAIRING THROUGH LAYOUT OF ACOUSTIC BLANKET

The characterization and understanding of the acoustic field within a launch vehicle's payload fairing (PLF) is critical to the qualification of a spacecraft and to the success of its mission ultimately. It has been studied since the beginning of the space program. In this paper, FE/BEM and SEA models are developed to predict the interior acoustic field of a payload firing over the full frequency range from 0 to 6300Hz. The interior acoustic field of an empty composite firing is test in an acoustics laboratory of Beijing Institute of Spacecraft Environment Engineering (BISEE). FE-BEM model in low frequency and SEA model in medium and high frequencies are thus validated. The acoustic blanket is used to reduce internal acoustic field of a payload firing. Its absorption coefficient is measured. In addition, the acoustic contribution degree of the firing to location of acoustic blanket treatment is also calculated. It is shown that medium cylindrical section is most sensitive region to noise reduction. The noise reduction of firing is obvious when cylindrical section is covered by acoustic blanket. However, the contribution degree of different region in cylindrical section is nearly the same. The noise reduction of firing depends on coverage not on layout when different region of cylindrical section is bonded acoustic blanket.