Accession Number : ADA300250

Title :   Control of Two and Three-Dimensional Wake Instabilities from Bluff-Bodies.

Descriptive Note : Final rept.

Corporate Author : LEHIGH UNIV BETHLEHEM PA DEPT OF MECHANICAL ENGINEERING AND MECHANICS

Personal Author(s) : Rockwell, Donald O.

PDF Url : ADA300250

Report Date : 28 FEB 1995

Pagination or Media Count : 11

Abstract : The detailed, instantaneous flow structure of the near-wake of a cylinder subjected to various classes of active (open-loop) and passive control has been characterized using both qualitative flow visualization and high-image-density particle image velocimetry (piv) developed in our laboratories. The first cinema PIV system allows acquisition of images that are highly resolved in both space and time. Concepts of timing of vortex formation, period-doubled patterns of vortices, and modulated and phase-locked systems of vortices are addressed for controlled oscillations of the cylinder. Three-dimensional patterns of instantaneous vorticity allow classification of the modes of response of the near-wake, providing a basis for formulating concepts for attenuation of vortex formation.

Descriptors :   *VORTICES, *WAKE, IMAGE PROCESSING, FREQUENCY MODULATION, FLOW VISUALIZATION, FLOW FIELDS, CYLINDRICAL BODIES, TWO DIMENSIONAL FLOW, UNSTEADY FLOW, VELOCIMETERS, RESEARCH MANAGEMENT, OSCILLATION, FLOW SEPARATION, INSTABILITY, PRESSURE DISTRIBUTION, REYNOLDS NUMBER, BOUNDARY LAYER CONTROL, PHASE LOCKED SYSTEMS, STEADY FLOW, THREE DIMENSIONAL FLOW, NONUNIFORM FLOW, HYDRODYNAMIC CONTROL SURFACES.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE