Flame thickness and conditional scalar dissipation rate in a premixed temporal turbulent reacting jet
Abstract
The flame structure corresponding to lean hydrogen–air premixed flames in intense sheared turbulence in the thin reaction zone regime is quantified from flame thickness and conditional scalar dissipation rate statistics, obtained from recent direct numerical simulation data of premixed temporallyevolving turbulent slot jet flames. It is found that, on average, these sheared turbulent flames are thinner than their corresponding planar laminar flames. Extensive analysis is performed to identify the reason for this counterintuitive thinning effect. The factors controlling the flame thickness are analyzed through two different routes i.e., the kinematic route, and the transport and chemical kinetics route. The kinematic route is examined by comparing the statistics of the normal strain rate due to fluid motion with the statistics of the normal strain rate due to varying flame displacement speed or selfpropagation. It is found that while the fluid normal straining is positive and tends to separate isoscalar surfaces, the dominating normal strain rate due to selfpropagation is negative and tends to bring the isoscalar surfaces closer resulting in overall thinning of the flame. The transport and chemical kinetics route is examined by studying the nonunity Lewis number effect on the premixed flames. The effects from the kinematic route aremore »
 Authors:
 Indian Institute of Science, Bangalore (India)
 Sandia National Lab. (SNLCA), Livermore, CA (United States)
 The Univ. of New South Wales, Sydney, NSW (Australia)
 Princeton Univ., Princeton, NJ (United States)
 Publication Date:
 Research Org.:
 Sandia National Lab. (SNLNM), Albuquerque, NM (United States)
 Sponsoring Org.:
 USDOE National Nuclear Security Administration (NNSA)
 OSTI Identifier:
 1372354
 Report Number(s):
 SAND20172193J
Journal ID: ISSN 00102180; PII: S0010218017300743
 Grant/Contract Number:
 AC0494AL85000
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Combustion and Flame
 Additional Journal Information:
 Journal Volume: 184; Journal Issue: C; Journal ID: ISSN 00102180
 Publisher:
 Elsevier
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; direct numerical simulations; detailed chemistry; flame thickness; conditional scalar dissipation rate; probability density functions
Citation Formats
Chaudhuri, Swetaprovo, Kolla, Hemanth, Dave, Himanshu L., Hawkes, Evatt R., Chen, Jacqueline H., and Law, Chung K. Flame thickness and conditional scalar dissipation rate in a premixed temporal turbulent reacting jet. United States: N. p., 2017.
Web. doi:10.1016/j.combustflame.2017.02.027.
Chaudhuri, Swetaprovo, Kolla, Hemanth, Dave, Himanshu L., Hawkes, Evatt R., Chen, Jacqueline H., & Law, Chung K. Flame thickness and conditional scalar dissipation rate in a premixed temporal turbulent reacting jet. United States. doi:10.1016/j.combustflame.2017.02.027.
Chaudhuri, Swetaprovo, Kolla, Hemanth, Dave, Himanshu L., Hawkes, Evatt R., Chen, Jacqueline H., and Law, Chung K. Fri .
"Flame thickness and conditional scalar dissipation rate in a premixed temporal turbulent reacting jet". United States.
doi:10.1016/j.combustflame.2017.02.027.
@article{osti_1372354,
title = {Flame thickness and conditional scalar dissipation rate in a premixed temporal turbulent reacting jet},
author = {Chaudhuri, Swetaprovo and Kolla, Hemanth and Dave, Himanshu L. and Hawkes, Evatt R. and Chen, Jacqueline H. and Law, Chung K.},
abstractNote = {The flame structure corresponding to lean hydrogen–air premixed flames in intense sheared turbulence in the thin reaction zone regime is quantified from flame thickness and conditional scalar dissipation rate statistics, obtained from recent direct numerical simulation data of premixed temporallyevolving turbulent slot jet flames. It is found that, on average, these sheared turbulent flames are thinner than their corresponding planar laminar flames. Extensive analysis is performed to identify the reason for this counterintuitive thinning effect. The factors controlling the flame thickness are analyzed through two different routes i.e., the kinematic route, and the transport and chemical kinetics route. The kinematic route is examined by comparing the statistics of the normal strain rate due to fluid motion with the statistics of the normal strain rate due to varying flame displacement speed or selfpropagation. It is found that while the fluid normal straining is positive and tends to separate isoscalar surfaces, the dominating normal strain rate due to selfpropagation is negative and tends to bring the isoscalar surfaces closer resulting in overall thinning of the flame. The transport and chemical kinetics route is examined by studying the nonunity Lewis number effect on the premixed flames. The effects from the kinematic route are found to couple with the transport and chemical kinetics route. In addition, the intermittency of the conditional scalar dissipation rate is also examined. It is found to exhibit a unique nonmonotonicity of the exponent of the stretched exponential function, conventionally used to describe probability density function tails of such variables. As a result, the nonmonotonicity is attributed to the detailed chemical structure of hydrogenair flames in which heat release occurs close to the unburnt reactants at near freestream temperatures.},
doi = {10.1016/j.combustflame.2017.02.027},
journal = {Combustion and Flame},
number = C,
volume = 184,
place = {United States},
year = {Fri Jul 07 00:00:00 EDT 2017},
month = {Fri Jul 07 00:00:00 EDT 2017}
}

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