Legendre C.,Free Field Technologies S.A |
Campos L.M.B.C.,University of Lisbon
29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014 | Year: 2014
A wave equation is obtained to describe the sound propagation in a unidirectional shear flow with linear velocity profile superimposed to a constant cross-flow, together with an impedance wall boundary condition, this represent the effect of a locally reacting liner with bias flow in presence of a shear flow. The wave equation is a third-order differential equation in the presence of cross-flow, and its general solution is a linear combination of three linearly independent MacLaurin series. The acoustic field in the boundary layer governed by the acousticvortical wave equation is matched through the pressure and horizontal and vertical velocity components to the acoustic field in a uniform free stream consisting of incident and reflected waves. In addition with the impedance boundary condition at the wall this specifies the pressure field in the whole domain and the reflection and transmission coefficients. These are plotted for several values of free stream and cross flow Mach numbers.