Model analysis theory and calculation for the sound propagation in a straight circular duct with multisegments in the presence of uniform flow

摘要

The modal analysis is applied to investigation the sound propagation in a straight circular duct with multi-segmented acoustical treatments. And the prediction model of sound propagation in the presence of uniform flow and shear flow is established. For a three-segmented circular duct (the middle segment is acoustic liner, the others are hard walls) in the present of uniform flow, the influence of the variations of resistance and reactance of liner on the in-duct suppression and sound power level attenuation due to forward travelling pressure and velocity components, is theoretically calculated. Finally, the optimization on operating parameters, resistance and reactance of liners are also presented and numerically calculated.