SBIR-STTR Award

MPAC and UMR are proposing development of an Acoustic Control System for high temperature gas flow in ducts. This control system is based on a passive inorganic acoustical coating. MPAC has developed and applied for a patent on a architectural acoustical control coating with unusually high wear resistance, a noise reduction coefficient of 0.5, and excellent low frequency damping. UMR has long experience in modeling acoustic treatment in ducts with high speed flow and has world class facilities for experimental characterization of acoustic materials and systems. The proposal team is committed to a phase one proof of concept deliverable consisting of passive coatings for application. This acoustic control coating, if successful, would provide a very low cost high reliability acoustical damping for hot gas structures.

Phase I demonstrated experimentally a very high temperature acoustically absorbing coating for ducted acoustics applications. High temperature survivability at 3500 deg F was demonstrated in the MSFC Plasma Jet Facility. Normal incidence acoustic absorption coefficient of 25 % was demonstrated in a standing wave test facility. Phase I work confirmed the possibility of production of acoustic coatings for application in ducted flows near the exhaust of a large rocket engine. The screening process for Phase I was unique in its emphasis on the practical development of a deliverable coating, as opposed to untested theoretical work or screening at unrealistic environmental conditions. In addition, work done late in Phase I produced a coating with an absorption coefficient of 47 % which has yet to be screened for high temperature survivability. Phase two has one objective and one deliverable: To produce and experimentally validate a fully working high temperature acoustical absorption duct lining material. Production involves optimizing the material through iterative reformulation, experimental validation involves acoustic and survival testing at conditions (specifically temperatures and sound intensities) relevant to the use environment. Additionally finite element modeling will be used to validate/refine the data collection apparatus as no such facility or testing has been done previously.