GUIDED ACOUSTIC-WAVE PROPAGATION IN A SHEAR-FLOW

The present work deals with the propagation of sound within a shear fl ow that takes place inside a two-dimensional rigid duct. Two kinds of hows are considered: a constant gradient shear flow and a shear flow w ith turbulent effects. A new analytical method based upon stratificati on that consists of dividing the guide into a number of uniform flow l ayers is proposed. This method enables the determination of the modal solutions for the complex potential in each layer for the upstream, do wnstream, propagative, and evanescent modes. Once these solutions have been calculated, the pressure profiles can be plotted for the duct se ction. The downstream ''quasi-plane'' mode is compared with results ob tained by various authors. The second part of the study consists of, u sing the previous results, estimating the effects of frequency and spe ed on the pressure profiles on the upper side of the duct in the prese nce of a source located in front of the duct.