TY - JOUR
T1 - Surface properties of turbulent premixed propane/air flames at various Lewis numbers
AU - Lee, T. W.
AU - North, G. L.
AU - Santavicca, D. A.
N1 - Funding Information:
The support for this research has been provided by the Air Force Office of Scientific Research under Grant AFOSR-87-O097, with Dr. Julian Tishkoff as program manager.
PY - 1993/6
Y1 - 1993/6
N2 - Surface properties of turbulent premixed flames including the wrinkled flame perimeter, fraction of the flame pocket perimeter, flame curvature, and orientation distributions have been measured for propane-air flames at Lewis numbers ranging from 0.98 to 1.86 and u′ SL = 1.42-5.71. The wrinkled flame perimeter is found to be greater for the thermodiffusively unstable Lewis number (Le < 1) by up to 30% in comparison to the most stable condition (Le = 1.86) tested, while the fraction of the flame pocket perimeter shows a similar tendency to be greater for Le < 1. The flame curvature probability density functions are nearly symmetric with respect to the zero mean at all Lewis numbers throughout the range of u′ SL tested, and show a much stronger dependence on the turbulence condition than on the Lewis number. Similarly, the flame orientation distributions show a trend from anisotropy toward a more uniform distribution with increasing u′ SL at a similar rate for all Lewis numbers. Thus, for turbulent premixed propane/air flames for a practical range of Lewis number from 0.98 to 1.86, the effect of Lewis number is primarily to affect the flame structures and thereby flame surface areas and flame pocket areas, while the flame curvature and orientation statistics are essentially determined by the turbulence properties.
AB - Surface properties of turbulent premixed flames including the wrinkled flame perimeter, fraction of the flame pocket perimeter, flame curvature, and orientation distributions have been measured for propane-air flames at Lewis numbers ranging from 0.98 to 1.86 and u′ SL = 1.42-5.71. The wrinkled flame perimeter is found to be greater for the thermodiffusively unstable Lewis number (Le < 1) by up to 30% in comparison to the most stable condition (Le = 1.86) tested, while the fraction of the flame pocket perimeter shows a similar tendency to be greater for Le < 1. The flame curvature probability density functions are nearly symmetric with respect to the zero mean at all Lewis numbers throughout the range of u′ SL tested, and show a much stronger dependence on the turbulence condition than on the Lewis number. Similarly, the flame orientation distributions show a trend from anisotropy toward a more uniform distribution with increasing u′ SL at a similar rate for all Lewis numbers. Thus, for turbulent premixed propane/air flames for a practical range of Lewis number from 0.98 to 1.86, the effect of Lewis number is primarily to affect the flame structures and thereby flame surface areas and flame pocket areas, while the flame curvature and orientation statistics are essentially determined by the turbulence properties.
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U2 - 10.1016/0010-2180(93)90144-R
DO - 10.1016/0010-2180(93)90144-R
M3 - Article
AN - SCOPUS:0027610020
SN - 0010-2180
VL - 93
SP - 445
EP - 456
JO - Combustion and Flame
JF - Combustion and Flame
IS - 4
ER -