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Title: Experimental Study of the Flowfield of a Two-Dimensional Premixed Turbulent Flame

A turbulent reacting shear layer in a premixed propane/air flow has been studied in a two dimensional combustor, with the flame stabilized behind a rearward facing streamlined step. Spark shadowgraphs show that in the range of velocities (7.5 to 22.5 m/sec corresponding to Reynolds numbers of .5 x 10{sup 4} cm{sup -1} to 1. 5 x 10{sup 4} cm{sup -1} ) and equivalence ratios (0.4 to 0.7) studied, the mixing layer is dominated by Brown~ Roshko type large coherent structures in both reacting and nonreacting flows. High speed schlieren movies show that these eddies are convected downstream and increase their size and spacing by combustion and coalescence with neighboring eddies. Tracing individual eddies shows, in the reacting shear layer, that, on the average, eddies accelerate as they move downstream with the highest acceleration close to the origin of the shear layer. Combustion is confined to these large structures which develop as a result of vortical action of the shear flow. On the average, the reacting eddies have a lower growth rate than nonreacting eddies. A turbulent boundary layer created by means of a tripping wire upstream of the edge of the step virtually eliminates the large coherent structures in themore » shear layer, while for the case in which the wire could not trigger the transition to turbulence, the large coherent structures dominated the reacting and nonreacting flows.« less
Authors:
;
Publication Date:
OSTI Identifier:
1068987
Report Number(s):
LBL-10790
Journal ID: ISSN 0001-1452
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIAA Journal; Journal Volume: 18; Journal Issue: 7
Publisher:
AIAA
Research Org:
Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
Sponsoring Org:
Environmental Energy Technologies Division
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING