Receptivity to Sound of an Elliptic Leading Edge on a Flat Plate.
Abstract
The leading edge receptivity to acoustic waves of two-dimensional bodies is investigated using a spatial solution of the Navier-Stokes equations in vorticity/stream function form in general curvilinear coordinates. The free-stream is composed of a uniform flow with a superposed periodic velocity fluctuation of small amplitude. The method follows that of Haddad & Corke(J. Fluid Mech.), 368, 1998 in which the solution for the basic flow and linearized perturbation flow are solved separately. The motivation for the work comes from physical experiments by Wei(M.S. Thesis, Arizona State Univ., 1994) and Rasmussen(M.S. Thesis, Arizona State Univ., 1992) for flat plates with elliptic leading edges, which showed frequency bands of higher Branch I receptivity. We investigated the same conditions in our simulations, as well as on a parabolic leading edge. The numerical simulations documented higher receptivity in frequency bands which were similar to the experiments. These however did not appear for the parabolic body. The results suggest an influence of the elliptic leading-edge/flat-plate joint as an additional site of receptivity which, along with the leading edge, provides a wave-length selection mechanism which favors certain frequencies through linear superposition.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1998
- Bibcode:
- 1998APS..DFD..AF09W