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Title: A comparison of the velocity and scalar spectra in premixed turbulent flames

Abstract

Frequency spectra for scalar and two velocity components in premixed methane-air turbulent {nu}-flames and stagnation flow-stabilized flames have been measured using laser light Mie scattering and laser Doppler anemometry techniques. To assist in interpreting the influence of flame crossing phenomenon on the scalar spectra, theoretical predictions of the spectra developed by Bray-Libby-Moss and by Bray-Libby were evaluated. The spectral slopes and most energetic frequencies of the scalar spectra were compared with those of the velocity components normal and tangential to the turbulent flame brush. In both configurations, the spectra of the normal velocity components are similar to the corresponding scalar spectra, demonstrating the coupling between velocity and scalar spectra. However, the most energetic frequencies, which are related to the flame crossing frequencies, are about an order of magnitude higher in the {nu}-flame than in the stagnation flames. Because this difference does not seem to be proportional to the difference in the mean velocities, the results imply that the spatial scale distribution in the two flame zones are not the same.

Authors:
;  [1];  [2]
  1. Lawrence Berkeley Lab., CA (USA). Applied Science Div.
  2. CRCCHT-CNRS, 45071 Orleans Cedex 2 (FR)
Publication Date:
OSTI Identifier:
5368676
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Combustion and Flame; (USA)
Additional Journal Information:
Journal Volume: 78:2; Journal ID: ISSN 0010-2180
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 42 ENGINEERING; AIR; FLAMES; TURBULENT FLOW; METHANE; MIXTURES; SPECTRA; VELOCITY; ALKANES; DISPERSIONS; FLUID FLOW; FLUIDS; GASES; HYDROCARBONS; ORGANIC COMPOUNDS; 400800* - Combustion, Pyrolysis, & High-Temperature Chemistry; 420400 - Engineering- Heat Transfer & Fluid Flow; 400102 - Chemical & Spectral Procedures

Citation Formats

Cheng, R K, Shepherd, I G, and Gokalp, I. A comparison of the velocity and scalar spectra in premixed turbulent flames. United States: N. p., 1989. Web. doi:10.1016/0010-2180(89)90126-0.
Cheng, R K, Shepherd, I G, & Gokalp, I. A comparison of the velocity and scalar spectra in premixed turbulent flames. United States. doi:10.1016/0010-2180(89)90126-0.
Cheng, R K, Shepherd, I G, and Gokalp, I. Wed . "A comparison of the velocity and scalar spectra in premixed turbulent flames". United States. doi:10.1016/0010-2180(89)90126-0.
@article{osti_5368676,
title = {A comparison of the velocity and scalar spectra in premixed turbulent flames},
author = {Cheng, R K and Shepherd, I G and Gokalp, I},
abstractNote = {Frequency spectra for scalar and two velocity components in premixed methane-air turbulent {nu}-flames and stagnation flow-stabilized flames have been measured using laser light Mie scattering and laser Doppler anemometry techniques. To assist in interpreting the influence of flame crossing phenomenon on the scalar spectra, theoretical predictions of the spectra developed by Bray-Libby-Moss and by Bray-Libby were evaluated. The spectral slopes and most energetic frequencies of the scalar spectra were compared with those of the velocity components normal and tangential to the turbulent flame brush. In both configurations, the spectra of the normal velocity components are similar to the corresponding scalar spectra, demonstrating the coupling between velocity and scalar spectra. However, the most energetic frequencies, which are related to the flame crossing frequencies, are about an order of magnitude higher in the {nu}-flame than in the stagnation flames. Because this difference does not seem to be proportional to the difference in the mean velocities, the results imply that the spatial scale distribution in the two flame zones are not the same.},
doi = {10.1016/0010-2180(89)90126-0},
journal = {Combustion and Flame; (USA)},
issn = {0010-2180},
number = ,
volume = 78:2,
place = {United States},
year = {1989},
month = {11}
}