Effects of acoustic and vortical disturbances on the turbulent boundary layer at free-stream Mach number 0.5 /

Abstract

An experimental investigation of the effects of free-stream disturbances on the development of a turbulent boundary layer is described. The data, obtained at a free-stream Mach number of 0.5, indicated: (1) compared to the baseline acoustic disturbances of 133 db, acoustic disturbances of up to 150 db did not significantly alter the turbulent boundary-layer skin friction, displacement thickness, or momentum thickness and (2) compared to the baseline vortical disturbances of 0.5 percent of the free-stream velocity, vortical disturbances of one percent of the free-stream velocity considerably altered the boundary-layer skin friction, displacement thickness, and momentum thickness, as well as their growth rates. (Author)."December 1977.""Final Report: July 1, 1974 -- June 30, 1976."Includes bibliographical references (pages 19-21).An experimental investigation of the effects of free-stream disturbances on the development of a turbulent boundary layer is described. The data, obtained at a free-stream Mach number of 0.5, indicated: (1) compared to the baseline acoustic disturbances of 133 db, acoustic disturbances of up to 150 db did not significantly alter the turbulent boundary-layer skin friction, displacement thickness, or momentum thickness and (2) compared to the baseline vortical disturbances of 0.5 percent of the free-stream velocity, vortical disturbances of one percent of the free-stream velocity considerably altered the boundary-layer skin friction, displacement thickness, and momentum thickness, as well as their growth rates. (Author).Report supported by the Air Force Systems Command and prepared by ARO, Inc, under Program Element,Mode of access: Internet