Development and Validation of Finite Element Approaches to Determine the Insertion Loss of Louvered Terminations including Parametric Investigations

Louvers are employed at the ends of HVAC ducts to direct airflow, provide weather protection, and attenuate noise. This details two finite element approaches that can be used to assess the acoustic attenuation from a louvered termination. In the first approach, plane wave propagation is assumed inside of a duct with a non-reflective source. On the receiver side, a baffled termination is assumed and the radiation condition is simulated using a non-reflective boundary condition called an automatically matched layer. In the second approach, a short aperture is placed between two infinite acoustic spaces. On the source side, a diffuse acoustic field is simulated using 20 monopole sources having random phase. The receiver side is modeled as before. For both approaches, the insertion loss is defined as the difference in sound power on the receiving side with and without the louver array. The second approach is compared with measurement with good agreement. The effect of different louver parameters including angle, length, and spacing, and the presence of sound absorptive lining is investigated using both approaches