Numerical method for prediction of duct break out sound power
- Publication Type:
- Conference Proceeding
- Proceedings of Meetings on Acoustics, 2019, 39, (1), pp. 022001
- Issue Date:
The acoustic design of duct systems requires consideration of both the noise propagating within a duct and also of the noise transmitted out through the duct walls into the environment. Control of this breakout noise can form a significant part of a noise control solution, and so understanding this phenomenon can lead to reduced material use. The breakout noise is investigated here using coupled structural-acoustic finite element models. Propagation along a waveguide with constant cross section is represented using a modal expansion of the acoustic pressure in the fluid and displacement in the duct walls. The free-field external environment requires an outer boundary condition, and for this purpose, a perfectly matched layer is applied at some distance from the elastic walls. The finite length of the waveguide is then enforced by coupling the fields to separate infinite length inlet and outlet ducts by the mode matching method. Transmitted power from the finite length duct is investigated when a noise source is placed in the inlet.
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