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Title: Turbulent opposed-jet flames: A critical benchmark experiment for combustion LES

Abstract

Turbulent opposed-jet configurations have gained attention as a challenging test case to validate the mixing and combustion models used in the simulation of turbulent combustion. In general, validation requires comprehensive experimental information on flow and scalar fields, and the emergence of combustion large-eddy simulation (CLES) necessitated more advanced diagnostics. These laser-optical techniques allow measurements not only of single-point statistics but of structural information of the flame, such as correlations, gradients, and structure functions. This paper presents thorough experimental and numerical investigations of one isothermal and two reacting turbulent opposed jets with fuel jets consisting of partially premixed methane. Its focus is on one configuration at and one configuration close to the highest possible Reynolds numbers where flames could be stabilized. The experimental data presented comprise information on axial velocity, main species concentrations, temperature, mixture fraction, scalar dissipation rate, joint probability density functions, and structure functions. These quantities are compared to results of highly resolved CLES to show the configuration's suitability as a critical benchmark for state-of-the art combustion LES.

Authors:
; ;  [1];  [2]
  1. FG Energie- und Kraftwerkstechnik, TU Darmstadt, 64287 Darmstadt (Germany)
  2. Department of Mechanical Engineering, Imperial College London, SW7 2AZ London (United Kingdom)
Publication Date:
OSTI Identifier:
20681468
Resource Type:
Journal Article
Resource Relation:
Journal Name: Combustion and Flame; Journal Volume: 143; Journal Issue: 4; Other Information: Elsevier Ltd. All rights reserved
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 03 NATURAL GAS; BENCHMARKS; FLAMES; TURBULENCE; JETS; COMBUSTION KINETICS; COMPUTERIZED SIMULATION; METHANE; COMBUSTION PRODUCTS

Citation Formats

Geyer, D., Dreizler, A., Janicka, J., and Kempf, A.. Turbulent opposed-jet flames: A critical benchmark experiment for combustion LES. United States: N. p., 2005. Web. doi:10.1016/j.combustflame.2005.08.032.
Geyer, D., Dreizler, A., Janicka, J., & Kempf, A.. Turbulent opposed-jet flames: A critical benchmark experiment for combustion LES. United States. doi:10.1016/j.combustflame.2005.08.032.
Geyer, D., Dreizler, A., Janicka, J., and Kempf, A.. Thu . "Turbulent opposed-jet flames: A critical benchmark experiment for combustion LES". United States. doi:10.1016/j.combustflame.2005.08.032.
@article{osti_20681468,
title = {Turbulent opposed-jet flames: A critical benchmark experiment for combustion LES},
author = {Geyer, D. and Dreizler, A. and Janicka, J. and Kempf, A.},
abstractNote = {Turbulent opposed-jet configurations have gained attention as a challenging test case to validate the mixing and combustion models used in the simulation of turbulent combustion. In general, validation requires comprehensive experimental information on flow and scalar fields, and the emergence of combustion large-eddy simulation (CLES) necessitated more advanced diagnostics. These laser-optical techniques allow measurements not only of single-point statistics but of structural information of the flame, such as correlations, gradients, and structure functions. This paper presents thorough experimental and numerical investigations of one isothermal and two reacting turbulent opposed jets with fuel jets consisting of partially premixed methane. Its focus is on one configuration at and one configuration close to the highest possible Reynolds numbers where flames could be stabilized. The experimental data presented comprise information on axial velocity, main species concentrations, temperature, mixture fraction, scalar dissipation rate, joint probability density functions, and structure functions. These quantities are compared to results of highly resolved CLES to show the configuration's suitability as a critical benchmark for state-of-the art combustion LES.},
doi = {10.1016/j.combustflame.2005.08.032},
journal = {Combustion and Flame},
number = 4,
volume = 143,
place = {United States},
year = {Thu Dec 01 00:00:00 EST 2005},
month = {Thu Dec 01 00:00:00 EST 2005}
}
  • The local scalar statistics of premixed flames in turbulent opposed streams has been studied by sheet laser tomography. The statistics collected on these flame edges provide information on the mean flame position, and the mean and standard deviations of local flamelet orientation and curvature. Emphasis is given to how these parameters vary through the flame brush as the flames are pushed toward extinction. The flames are essentially planar in the mean and the probability density function (pdf) of flamelet orientation in symmetric about this mean orientation. The standard deviation of flame angle is essentially constant throughout the flame brush, butmore » varies strongly at the leading and trailing flame edges. The mean curvature of these flame is positive (i.e., concave to products) at the leading edge of the flame and negative at its trailing edge. Similar to the flame angle, the standard deviation of flame curvature is also constant throughout most of the central portion of the flame brush. As the mean nozzle exit velocity and the turbulence intensity are increased to bring the flame nearer to extinction, the individual flame brushes thicken as much as 50%. The standard deviations of flame angle an curvature also increase but more modestly. An unexpected result of the data collected is the differences between the upper and lower flames, which is probably an effect of buoyancy. The lower flame is consistently and significantly more wrinkled than the upper flame, resulting in the lower brush being thicker by as much as 25% and having larger standard deviations of flame angle and curvature than the upper flame.« less
  • No abstract prepared.
  • The properties of chain ignition of silane (SiH/sub 4/) gas have been studied under reduced pressures by several previous researchers, but the flame properties at ordinary pressures seem to be very rarely studied in spite of the fact that this gas is now widely used in semiconductor manufacture. Very recently other researchers reported a counterflow diffusion flame technique applied to studying the SiO/sub x/ formation from silane in the flame of H/sub 2//O/sub 2/, but the properties of self sustaining flames of silane itself with air are not made clear.
  • This paper reports on an opposed-jet diffusion flame burner that was used in conjunction with an emission infrared spectrometer to study the effects of the addition of methyl bromide on the combustion of methane with air. An optical system permitted incremental scanning of a laminar diffusion flame formed between two horizontally opposed burner tubes. The image of the flat flame was focused on an auxiliary slit of the spectrometer by optical mirrors and scanned by moving the slit passed the image. For a methane-air flame with an overall stoichiometric ratio, {phi}, of 0.86, the spectra for the 3700-2400 cm{sup {minus}1}more » region (H{sub 2}O, OH, CO{sub 2}, CH{sub 3}, and HCHO bands) and 2400 to 2000 cm{sup {minus}1} (CO and CO{sub 2} bands) were compared with the spectra obtained when methyl bromide was added to the air-side of the burner. Supplementary measurements were made on methane-air and methane-oxygen-nitrogen flames with {phi} values in the range of 0.74 - 2.0. In some cases, the methane was diluted with nitrogen, and the methyl bromide was added to either the fuel or the air side of the burner.« less