Portable Methane Flux Meter

Not Available Dynamic Structures and Materials proposes to develop dissipative acoustic arrays for the control of interior noise in launch vehicle payload fairings. The innovation in this work is the use of discrete noise control sources that utilize feedback control to dissipate acoustic energy. Acoustic energy dissipation is a robust method of reducing sound pressure levels in the interior of the payload fairings. The goal of the research is to provide payloads with a quieter ride to orbit through new methods of active acoustic suppression in launch vehicles. The motivation for this work is the control of low-frequency in small to medium-sized launch vehicle payload fairings. Low-frequency noise is a problem in launch vehicle fairings due to the lack of significant energy dissipation below 200 to 300 Hz. The conventional method for reducing fairing sound pressure levels is to line the interior with sound absorbing acoustic blankets. Although very effective at higher frequencies, acoustic blankets provide less sound absorption at frequencies in which the acoustic wavelength is large compared to the thickness of the material. The effectiveness of the passive acoustic treatment is limited at low frequencies by the thickness of the blanket material.