Ultra-Quiet COTS Module Unit Enclosure

Pneumafil, Corporation, along with Engineering Technology Center (ETC), proposes to develop a cost effective unit enclosure that supports installation of COTS (Commercial Off The Shelf) modules in the submarine sphere hard deck mounting environment which minimizes structure borne noise, attenuates shock, provides adequate cooling and EMI protection. Engineering analyses will include an assessment of the enclosure performance requirements such as air borne and structure borne noise levels, shock accelerations and space limitations. The dynamics of the standard cooling fan will be characterized including flow rates, blade diameter and pitch. Also, the type, location and ducting of the quiet air/water heat exchanger will be examined. Several passive and active noise suppression techniques will be explored. Passive techniques to be considered: innovative 2 stage isolation system, low wave speed damping in structural voids, multiple mounting schemes and *quiet* air ducts. Active techniques will include: DC fan usage with thermal and speed controllers, shakers for structure borne noise cancellation and speakers for air borne noise cancellation. Finally, as part of the Phase I Option, a prototype enclosure will be fabricated and the producibility evaluated. This will lead to performance testing, an acoustic numerical model, a structural model and further refinement in Phase II.