Improved Damping Modeling for Afterburners

In phase I of this SBIR project we propose the development of a software tool for designing passive acoustic treatment for adding acoustic damping to the low-frequency (<1000 Hz) modes most sympathetic to heat release perturbation in an augmentor, i.e., the first tangential and first radial modes. Considering that the resonant frequencies of these modes are reasonably constant (do not change appreciably with operating conditions) and their corresponding frequencies are spaced apart from each other, passive tuned acoustic treatment is proposed as the candidate solution. The physics-based software tool will be considering the effects of grazing flow, cooling flow, and distributed (not discrete) dynamics of the absorber itself. The design tool will be developed in COMSOL finite element analysis environment. The software tool will be used to design 2 acoustic dampers tuned to the first tangential and first radial modes of an augmentor with the same geometry and attributes as that of F136 engine . The effectiveness of the designed dampers will be numerically demonstrated by implementing them in the finite element aeroacoustic model of the candidate augmentor.