Accession Number:

ADA190503

Title:

Interaction of a Two-Dimensional Bluff Body and Incompressible Jet and Annulus Flows

Descriptive Note:

Master thesis

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING

Personal Author(s):

Report Date:

1987-12-01

Pagination or Media Count:

166.0

Abstract:

A particular interaction of bluff body and jet flows was studied using two dimensional slot jet aspect ratio 50 surrounded by a two dimensional bluff body. The coflowing system used air in the annulus and nitrogen in the jet. Flow visualization identified flow patterns containing large vortex structures were observed as jet velocities changed. Laser Doppler Anenometry measurements of instantaneous velocities were examined to characterize the flowfield details, and high speed movies provided qualitative insight into flow dynamics. The concept of jet and annulus fields is introduced. The jet field is the region above the bluff body that extends six or seven slot widths downstream, and the annulus field is the region above the jet field. The annulus flow dictates the flowfield dynamics in the annulus field up to jet-to- annulus velocity ratios of 1.45. The jet is responsible for the formation of the large-scale structures and dominates the flow in the jet field. Jet domination of the entire flowfield is seen at velocity ratios of 1.45 and above. Mie scattering was used to determine shedding frequencies of the large structures. Strouhal number based on jet velocity and slot which was a constant. 0.098.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE