Gas flow sound attenuation device

Abstract: The gas flow sound attenuation device includes a number of variations each having at least one pressure pulse reflecting chamber, i.e., a Helmholtz chamber, installed in axial alignment with the upstream gas flow. Gas flow is transferred laterally externally to the chamber, with the single opening of the chamber receiving substantially all incoming pressure pulse energy to maximize the reflection and canceling of those pulses back into the upstream duct. The device may incorporate any practicable number of chambers, so long as each has at least some length of upstream pipe or duct axially aligned with the chamber opening. The chambers may have any practicable shape and/or may include internal baffling. The device may be applied to any gas flow system, e.g., heating, ventilation, and air conditioning systems, but is particularly effective in reducing the sound output of internal combustion engine exhaust systems.