Simulation of noise propagation through heating ventilation and air conditioning ductwork

Noise primarily propagates through the airspace or breaks out through the walls of HVAC ductwork. Finite element analysis was used to assess the noise attenuation of each of these paths. Specifically, the insertion loss and breakout transmission loss were assessed for both bare and lined ductwork. Sound absorptive lining was modeled using poroelastic finite elements and the ductwork itself was modeled using shell and beam elements. A diffuse field was approximated at the source using a collection of monopole sources having random phase. Results were compared to measurement with good agreement. Several conclusions can be made regarding noise transmission in large ducts that should be transferable to other industries.