Vortex system evolution in 2- and 3-D swept trailing edge flows

Instability wavefront orientation and vortex system interaction were studied in a swept-trailing-edge mixing layer and in a slanted nozzle jet flowfield at low subsonic velocities. Flow visualization and image processing, and hot-wire data comprised the main body of experimental observations. The response of full-span wave systems of swept and unswept orientation were documented as a function of acoustic excitation introduced through a thin slot at the trailing edge. The lateral spreading of a wave system with only partial-span excitation was shown to be asymmetrical in a swept mixing layer. The jet flowfield was studied using a simultaneous axial and transverse laser sheet illumination. Excitation frequency dependence and amplitude dependence of instability wave system orientation was characterized. Digitized flow visualization images were decomposed to show the axial and helical shear layer modes.