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Title: A tomographic study of premixed turbulent stagnation point flames

Abstract

The high speed tomographic technique has been used to study premixed flame propagation in stagnation flow stabilized flames. Studies are performed on CH4/Air and C2H4/Air flames with equivalence ratios ranging from 0.75 to 1.0. The gas velocity at the nozzle exit is 5 m/s, the turbulence intensity is varied from 5% to 7% and the turbulence Reynolds number is 70. The light source is a copper vapor laser which produces 20ns, 5 mJ pulses at a 4KHz repetition rate. Cylindrical lenses transform the 38 mm circular laser beam to a sheet 50 mm high and 0.6 mm thick. A high speed Fastax camera is used to record the tomographic images. The films are digitized and the flame front extracted from the images by a thresholding technique. A fractal analysis was performed on the flame boundaries in order to characterize the flame geometry and provide an estimate of the flame surface area. The flame area increase was found to give a reasonable estimate of the burning rate when compared with other methods if the effects of flow tube divergence were considered. Characteristic wrinkle sizes were found to be much larger than the length scales of the turbulence in the reactant stream.more » 8 refs., 5 figs., 2 tabs.« less

Authors:
; ;  [1]
  1. Lawrence Berkeley Lab., CA (USA)
Publication Date:
Research Org.:
Lawrence Berkeley Lab., CA (USA)
Sponsoring Org.:
USDOD; DOE/ER
OSTI Identifier:
5372256
Report Number(s):
LBL-27904; CONF-8910289-2
ON: DE90002462; CNN: F-44620-76-C-0083
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Conference
Resource Relation:
Conference: Western States Section meeting of the Combustion Institute, Livermore, CA (USA), 23-24 Oct 1989
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; FLAME PROPAGATION; TOMOGRAPHY; ALKENES; COMBUSTION PROPERTIES; MATHEMATICAL MODELS; METHANE; NOZZLES; STAGNATION POINT; TURBULENCE; ALKANES; DIAGNOSTIC TECHNIQUES; HYDROCARBONS; ORGANIC COMPOUNDS; 400800* - Combustion, Pyrolysis, & High-Temperature Chemistry

Citation Formats

Shepherd, I G, Cheng, R K, Goix, P, and California Univ., Berkeley, CA. A tomographic study of premixed turbulent stagnation point flames. United States: N. p., 1989. Web.
Shepherd, I G, Cheng, R K, Goix, P, & California Univ., Berkeley, CA. A tomographic study of premixed turbulent stagnation point flames. United States.
Shepherd, I G, Cheng, R K, Goix, P, and California Univ., Berkeley, CA. Sun . "A tomographic study of premixed turbulent stagnation point flames". United States.
@article{osti_5372256,
title = {A tomographic study of premixed turbulent stagnation point flames},
author = {Shepherd, I G and Cheng, R K and Goix, P and California Univ., Berkeley, CA},
abstractNote = {The high speed tomographic technique has been used to study premixed flame propagation in stagnation flow stabilized flames. Studies are performed on CH4/Air and C2H4/Air flames with equivalence ratios ranging from 0.75 to 1.0. The gas velocity at the nozzle exit is 5 m/s, the turbulence intensity is varied from 5% to 7% and the turbulence Reynolds number is 70. The light source is a copper vapor laser which produces 20ns, 5 mJ pulses at a 4KHz repetition rate. Cylindrical lenses transform the 38 mm circular laser beam to a sheet 50 mm high and 0.6 mm thick. A high speed Fastax camera is used to record the tomographic images. The films are digitized and the flame front extracted from the images by a thresholding technique. A fractal analysis was performed on the flame boundaries in order to characterize the flame geometry and provide an estimate of the flame surface area. The flame area increase was found to give a reasonable estimate of the burning rate when compared with other methods if the effects of flow tube divergence were considered. Characteristic wrinkle sizes were found to be much larger than the length scales of the turbulence in the reactant stream. 8 refs., 5 figs., 2 tabs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1989},
month = {10}
}

Conference:
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