Flame Front Geometry and Stretch During Interactions of Premixed Flames with Vortices

T. W. Lee; D. A. Santavicca

doi:10.1080/00102209308907611

Flame Front Geometry and Stretch During Interactions of Premixed Flames with Vortices

T. W. Lee, D. A. Santavicca

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

Flame front geometry and flame stretch during interactions of premixed flames with vortices at various configurations are computationally investigated using a kinematical relationship between vortex-induced velocity and flame propagation velocity, in conjunction with Lagrangian coordinates to represent the flame front. The maximum flame stretch that can occur during an interaction with a single vortex is found to be very close to U_θ/r_m+ S_L/2r_m, while the mean flame stretch has a maximum that asymptotes to 18–23% of this value for vortex radii between 1.25 and 5.0 mm as U_θ/S_Lis increased to 2. For flames interacting with a counter-rotating vortex pair, the flame stretch near the flow symmetry axis increases when the spacing between the vortices increase to align the velocity vectors with the flame front; while the flame stretch away from this region is relatively independent of the action of the opposite vortex and is determined primarily by the vortex velocity and length scale similar to the single vortex case. For flame contours caused by vortex arrays, the flame curvature scales more strongly with vortex size than vortex velocity; and the mean flame curvatures for both vortex arrays and a single vortex are bounded between I/d_mand l/(2d_m) except in an instance where the vortex produces negligible wrinkles on the flame front. The effect of decreasing the tangential spacing in the vortex array is to increase the coupling of actions of adjacent vortices which leads to an increase in flame area and a positive shift in the flame curvature pdf; while variations of normal vortex spacing have less effect on the flame front geometry. The maximum flame stretch for flames interacting with vortex arrays is found to be close to the value caused by a single vortex, whereas the mean flame stretch and higher statistical moments are significantly different due to the additional strains caused by the coupling of actions of adjacent vortices.

Original language	English (US)
Pages (from-to)	211-229
Number of pages	19
Journal	Combustion science and technology
Volume	90
Issue number	1-4
DOIs	https://doi.org/10.1080/00102209308907611
State	Published - Apr 1 1993
Externally published	Yes

ASJC Scopus subject areas

General Chemistry
General Chemical Engineering
Fuel Technology
Energy Engineering and Power Technology
General Physics and Astronomy

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10.1080/00102209308907611

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@article{d7ea635f5a514d21984531249fb673b7,

title = "Flame Front Geometry and Stretch During Interactions of Premixed Flames with Vortices",

abstract = "Flame front geometry and flame stretch during interactions of premixed flames with vortices at various configurations are computationally investigated using a kinematical relationship between vortex-induced velocity and flame propagation velocity, in conjunction with Lagrangian coordinates to represent the flame front. The maximum flame stretch that can occur during an interaction with a single vortex is found to be very close to Uθ/rm+ SL/2rm, while the mean flame stretch has a maximum that asymptotes to 18–23% of this value for vortex radii between 1.25 and 5.0 mm as Uθ/SLis increased to 2. For flames interacting with a counter-rotating vortex pair, the flame stretch near the flow symmetry axis increases when the spacing between the vortices increase to align the velocity vectors with the flame front; while the flame stretch away from this region is relatively independent of the action of the opposite vortex and is determined primarily by the vortex velocity and length scale similar to the single vortex case. For flame contours caused by vortex arrays, the flame curvature scales more strongly with vortex size than vortex velocity; and the mean flame curvatures for both vortex arrays and a single vortex are bounded between I/dmand l/(2dm) except in an instance where the vortex produces negligible wrinkles on the flame front. The effect of decreasing the tangential spacing in the vortex array is to increase the coupling of actions of adjacent vortices which leads to an increase in flame area and a positive shift in the flame curvature pdf; while variations of normal vortex spacing have less effect on the flame front geometry. The maximum flame stretch for flames interacting with vortex arrays is found to be close to the value caused by a single vortex, whereas the mean flame stretch and higher statistical moments are significantly different due to the additional strains caused by the coupling of actions of adjacent vortices.",

author = "Lee, {T. W.} and Santavicca, {D. A.}",

note = "Funding Information: The support for this research has been provided in pan by the Air Force Office of Scientific Research under Grant AFOSR-90-0025, Dr. Julian TishkoH as program m o n i t ~",

year = "1993",

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doi = "10.1080/00102209308907611",

language = "English (US)",

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AU - Lee, T. W.

AU - Santavicca, D. A.

N1 - Funding Information: The support for this research has been provided in pan by the Air Force Office of Scientific Research under Grant AFOSR-90-0025, Dr. Julian TishkoH as program m o n i t ~

PY - 1993/4/1

Y1 - 1993/4/1

N2 - Flame front geometry and flame stretch during interactions of premixed flames with vortices at various configurations are computationally investigated using a kinematical relationship between vortex-induced velocity and flame propagation velocity, in conjunction with Lagrangian coordinates to represent the flame front. The maximum flame stretch that can occur during an interaction with a single vortex is found to be very close to Uθ/rm+ SL/2rm, while the mean flame stretch has a maximum that asymptotes to 18–23% of this value for vortex radii between 1.25 and 5.0 mm as Uθ/SLis increased to 2. For flames interacting with a counter-rotating vortex pair, the flame stretch near the flow symmetry axis increases when the spacing between the vortices increase to align the velocity vectors with the flame front; while the flame stretch away from this region is relatively independent of the action of the opposite vortex and is determined primarily by the vortex velocity and length scale similar to the single vortex case. For flame contours caused by vortex arrays, the flame curvature scales more strongly with vortex size than vortex velocity; and the mean flame curvatures for both vortex arrays and a single vortex are bounded between I/dmand l/(2dm) except in an instance where the vortex produces negligible wrinkles on the flame front. The effect of decreasing the tangential spacing in the vortex array is to increase the coupling of actions of adjacent vortices which leads to an increase in flame area and a positive shift in the flame curvature pdf; while variations of normal vortex spacing have less effect on the flame front geometry. The maximum flame stretch for flames interacting with vortex arrays is found to be close to the value caused by a single vortex, whereas the mean flame stretch and higher statistical moments are significantly different due to the additional strains caused by the coupling of actions of adjacent vortices.

AB - Flame front geometry and flame stretch during interactions of premixed flames with vortices at various configurations are computationally investigated using a kinematical relationship between vortex-induced velocity and flame propagation velocity, in conjunction with Lagrangian coordinates to represent the flame front. The maximum flame stretch that can occur during an interaction with a single vortex is found to be very close to Uθ/rm+ SL/2rm, while the mean flame stretch has a maximum that asymptotes to 18–23% of this value for vortex radii between 1.25 and 5.0 mm as Uθ/SLis increased to 2. For flames interacting with a counter-rotating vortex pair, the flame stretch near the flow symmetry axis increases when the spacing between the vortices increase to align the velocity vectors with the flame front; while the flame stretch away from this region is relatively independent of the action of the opposite vortex and is determined primarily by the vortex velocity and length scale similar to the single vortex case. For flame contours caused by vortex arrays, the flame curvature scales more strongly with vortex size than vortex velocity; and the mean flame curvatures for both vortex arrays and a single vortex are bounded between I/dmand l/(2dm) except in an instance where the vortex produces negligible wrinkles on the flame front. The effect of decreasing the tangential spacing in the vortex array is to increase the coupling of actions of adjacent vortices which leads to an increase in flame area and a positive shift in the flame curvature pdf; while variations of normal vortex spacing have less effect on the flame front geometry. The maximum flame stretch for flames interacting with vortex arrays is found to be close to the value caused by a single vortex, whereas the mean flame stretch and higher statistical moments are significantly different due to the additional strains caused by the coupling of actions of adjacent vortices.

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ER -

Flame Front Geometry and Stretch During Interactions of Premixed Flames with Vortices

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