Accession Number:

ADA199989

Title:

Studies of Unsteadiness in Boundary Layers

Descriptive Note:

Annual technical rept. 1 May 1987-30 Apr 1988

Corporate Author:

UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF AEROSPACE ENGINEERING

Report Date:

1988-07-13

Pagination or Media Count:

18.0

Abstract:

Experimental and theoretical efforts aimed at clarifying and revealing important dynamical features of several turbulent shear flows are described. The flows studied include boundary layers, jets, wakes and separated flows on lifting surfaces. Significant progress has been made through experimental studies toward understanding 1 Unsteady, near wall processes in turbulent boundary layers responsible for the production of turbulent energy 2 Procedures for enhancing entrainment and mixing in hot jets by passively contouring the jet exit and 3 Characteristics of boundary layer separation and its control on lifting surfaces in unsteady flows. Theoretical studies on the temporal and spatial structure in blunt body wakes have revealed the necessary conditions under which global, self sustained oscillations appear and have provided firm criteria for specifying the frequency of these oscillations. The theory has been employed to described the preferred mode in jets. In addition, A Theory description of the appearance of the spatial chaos in wake shear layers, and its representation in terms of a one dimensional map, has been provided.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE