Direct comparison of turbulent burning velocity and flame surface properties in turbulent premixed flames

Taewoo Lee, S. J. Lee

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Direct comparison of the turbulent burning velocity (obtained from flame speeds) to the flame perimeter ratio has been made in turbulent premixed flames propagating freely downward for propane/air mixtures at various equivalence ratios, with u′/SL of ranging from 1.4 to 5.3. The turbulent flame speed ranged from 2.6 to about 7 times the laminar flame speed at high turbulence intensities, while the flame perimeter ratio ranges from 1.4 to 3.3. In the current freely propagating flames, the global flame curvature can lead to an enhancement of the flame speed by a factor of up to 3.5. This global flame curvature is attributable to the wall heat loss in the current burner configuration, and flame brush thickness has been used as a measure of the global flame curvature. For flames involving coupling of the globally curved flame geometry with flow divergence or any flow non-uniformity, correcting for this geometrical effect requires a careful consideration of the flame topology and flow field. The difference between the observed flame speed and the 2-D flame perimeter ratio, after correcting for the global flame curvature effect, is attributed to the fact that the flame wrinkles in three-dimensions are associated with a larger flame surface area than that determined from the flame perimeter ratio data. This also points to a need to better understand the 3-D geometrical effects including the global flame curvature and the local flame wrinkle structure in turbulent premixed flames. The observed turbulent flame speed data for the most part follow the flame speed models of Bray and Damkohler, wherein the flame surface area increase is modeled as a function of turbulence and thermochemical properties. The above results, taken together, indicate that the fundamental assumption that the turbulent flame speed depends primarily on the increased flame surface area is valid. This concept can be used to estimate the turbulent flame speed within reasonable accuracy provided that the 3-D flame effects associated with the global flame curvature and local flame wrinkle structure are considered.

Original languageEnglish (US)
Pages (from-to)492-502
Number of pages11
JournalCombustion and Flame
Volume132
Issue number3
DOIs
StatePublished - Feb 1 2003

Fingerprint

turbulent flames
premixed flames
surface properties
Surface properties
flames
Turbulence
curvature
Propane
Brushes
Heat losses
Fuel burners
Flow fields
Topology
Geometry

Keywords

  • Burning velocity
  • Flame speed
  • Flame surface
  • Turbulent premixed flames

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Fuel Technology
  • Mechanical Engineering

Cite this

Direct comparison of turbulent burning velocity and flame surface properties in turbulent premixed flames. / Lee, Taewoo; Lee, S. J.

In: Combustion and Flame, Vol. 132, No. 3, 01.02.2003, p. 492-502.

Research output: Contribution to journalArticle

@article{446ea95f089c4867bba93fffdffef63b,
title = "Direct comparison of turbulent burning velocity and flame surface properties in turbulent premixed flames",
abstract = "Direct comparison of the turbulent burning velocity (obtained from flame speeds) to the flame perimeter ratio has been made in turbulent premixed flames propagating freely downward for propane/air mixtures at various equivalence ratios, with u′/SL of ranging from 1.4 to 5.3. The turbulent flame speed ranged from 2.6 to about 7 times the laminar flame speed at high turbulence intensities, while the flame perimeter ratio ranges from 1.4 to 3.3. In the current freely propagating flames, the global flame curvature can lead to an enhancement of the flame speed by a factor of up to 3.5. This global flame curvature is attributable to the wall heat loss in the current burner configuration, and flame brush thickness has been used as a measure of the global flame curvature. For flames involving coupling of the globally curved flame geometry with flow divergence or any flow non-uniformity, correcting for this geometrical effect requires a careful consideration of the flame topology and flow field. The difference between the observed flame speed and the 2-D flame perimeter ratio, after correcting for the global flame curvature effect, is attributed to the fact that the flame wrinkles in three-dimensions are associated with a larger flame surface area than that determined from the flame perimeter ratio data. This also points to a need to better understand the 3-D geometrical effects including the global flame curvature and the local flame wrinkle structure in turbulent premixed flames. The observed turbulent flame speed data for the most part follow the flame speed models of Bray and Damkohler, wherein the flame surface area increase is modeled as a function of turbulence and thermochemical properties. The above results, taken together, indicate that the fundamental assumption that the turbulent flame speed depends primarily on the increased flame surface area is valid. This concept can be used to estimate the turbulent flame speed within reasonable accuracy provided that the 3-D flame effects associated with the global flame curvature and local flame wrinkle structure are considered.",
keywords = "Burning velocity, Flame speed, Flame surface, Turbulent premixed flames",
author = "Taewoo Lee and Lee, {S. J.}",
year = "2003",
month = "2",
day = "1",
doi = "10.1016/S0010-2180(02)00495-9",
language = "English (US)",
volume = "132",
pages = "492--502",
journal = "Combustion and Flame",
issn = "0010-2180",
publisher = "Elsevier Inc.",
number = "3",

}

TY - JOUR

T1 - Direct comparison of turbulent burning velocity and flame surface properties in turbulent premixed flames

AU - Lee, Taewoo

AU - Lee, S. J.

PY - 2003/2/1

Y1 - 2003/2/1

N2 - Direct comparison of the turbulent burning velocity (obtained from flame speeds) to the flame perimeter ratio has been made in turbulent premixed flames propagating freely downward for propane/air mixtures at various equivalence ratios, with u′/SL of ranging from 1.4 to 5.3. The turbulent flame speed ranged from 2.6 to about 7 times the laminar flame speed at high turbulence intensities, while the flame perimeter ratio ranges from 1.4 to 3.3. In the current freely propagating flames, the global flame curvature can lead to an enhancement of the flame speed by a factor of up to 3.5. This global flame curvature is attributable to the wall heat loss in the current burner configuration, and flame brush thickness has been used as a measure of the global flame curvature. For flames involving coupling of the globally curved flame geometry with flow divergence or any flow non-uniformity, correcting for this geometrical effect requires a careful consideration of the flame topology and flow field. The difference between the observed flame speed and the 2-D flame perimeter ratio, after correcting for the global flame curvature effect, is attributed to the fact that the flame wrinkles in three-dimensions are associated with a larger flame surface area than that determined from the flame perimeter ratio data. This also points to a need to better understand the 3-D geometrical effects including the global flame curvature and the local flame wrinkle structure in turbulent premixed flames. The observed turbulent flame speed data for the most part follow the flame speed models of Bray and Damkohler, wherein the flame surface area increase is modeled as a function of turbulence and thermochemical properties. The above results, taken together, indicate that the fundamental assumption that the turbulent flame speed depends primarily on the increased flame surface area is valid. This concept can be used to estimate the turbulent flame speed within reasonable accuracy provided that the 3-D flame effects associated with the global flame curvature and local flame wrinkle structure are considered.

AB - Direct comparison of the turbulent burning velocity (obtained from flame speeds) to the flame perimeter ratio has been made in turbulent premixed flames propagating freely downward for propane/air mixtures at various equivalence ratios, with u′/SL of ranging from 1.4 to 5.3. The turbulent flame speed ranged from 2.6 to about 7 times the laminar flame speed at high turbulence intensities, while the flame perimeter ratio ranges from 1.4 to 3.3. In the current freely propagating flames, the global flame curvature can lead to an enhancement of the flame speed by a factor of up to 3.5. This global flame curvature is attributable to the wall heat loss in the current burner configuration, and flame brush thickness has been used as a measure of the global flame curvature. For flames involving coupling of the globally curved flame geometry with flow divergence or any flow non-uniformity, correcting for this geometrical effect requires a careful consideration of the flame topology and flow field. The difference between the observed flame speed and the 2-D flame perimeter ratio, after correcting for the global flame curvature effect, is attributed to the fact that the flame wrinkles in three-dimensions are associated with a larger flame surface area than that determined from the flame perimeter ratio data. This also points to a need to better understand the 3-D geometrical effects including the global flame curvature and the local flame wrinkle structure in turbulent premixed flames. The observed turbulent flame speed data for the most part follow the flame speed models of Bray and Damkohler, wherein the flame surface area increase is modeled as a function of turbulence and thermochemical properties. The above results, taken together, indicate that the fundamental assumption that the turbulent flame speed depends primarily on the increased flame surface area is valid. This concept can be used to estimate the turbulent flame speed within reasonable accuracy provided that the 3-D flame effects associated with the global flame curvature and local flame wrinkle structure are considered.

KW - Burning velocity

KW - Flame speed

KW - Flame surface

KW - Turbulent premixed flames

UR - http://www.scopus.com/inward/record.url?scp=0037289684&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037289684&partnerID=8YFLogxK

U2 - 10.1016/S0010-2180(02)00495-9

DO - 10.1016/S0010-2180(02)00495-9

M3 - Article

VL - 132

SP - 492

EP - 502

JO - Combustion and Flame

JF - Combustion and Flame

SN - 0010-2180

IS - 3

ER -