Acoustics in variable area duct - Finite element and finite difference comparisons to experiment

Plane wave sound propagation without flow in a rectangular duct with a converging-diverging area variation is studied experimentally and theoretically. The area variation was of sufficient magnitude to produce large reflections and induce modal scattering. The rms pressure and phase angle on both the flat and curved surface were measured and tabulated. The "steady"-state finite element theory of Astley and Eversman and the transient finite difference theory of White are in good agreement with the data. It is concluded that numerical finite difference and finite element theories appear ideally suited for handling duct propagation problems which encounter large area variations. f* h * //* J k L* P p P0 S t U

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