The unlined 3D duct and its yz cross-section.
The xy cross-section of the unlined 3D duct.
The characteristic function for the unlined 3D duct (symmetric modes, clamped corners) plotted for (a) real and (b) imaginary arguments at 600 Hz.
Clamped corners: (a) Phase speeds of the unattenuated symmetric (solid) and anti-symmetric (dashed) waves plotted against frequency; (b) location of the symmetric (circles) and anti-symmetric (stars) roots in the complex s-plane at 600 Hz.
Pin-jointed corners: (a) Phase speeds of the unattenuated waves plotted against frequency; (b) location of the roots in the complex s-plane at 600 Hz.
The xy cross-sections of (a) the lined 3D duct (Sec. III); (b) the drum-like silencer (Sec. IV).
Lined duct: (a) Location of the non-dimensional roots in the complex s-plane at 170 Hz (the two least attenuated roots marked by triangles); (b) path in the complex plane along which the dimensional least attenuated roots move as frequency increases (the larger points indicate the frequencies 270 and 617 Hz, respectively).
The axial attenuation (logarithmic scale) for the two least attenuated roots [dashed curve corresponds to the upper triangle in Fig. 7(a)].
Drum-like silencer: Phase speeds for (a) Tz = Tx = 750; (b) Tx = 5, Tz = 750.
Drum-like silencer: Phase speeds for Tx = 750, Tz = 5; triangles indicate that for the fundamental coupled mode of the corresponding 2D case.
Article metrics loading...
Full text loading...