TY - JOUR
T1 - Conditional moment closure modeling of turbulent nonpremixed combustion in diluted hot coflow
AU - Kim, Seung Hyun
AU - Huh, Kang Y.
AU - Dally, Bassam
N1 - Funding Information:
This work is supported by the BK21 project of the Ministry of Education and the Combustion Engineering Research Center at Korea Advanced Institute of Science and Technology.
Publisher Copyright:
© 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
PY - 2005
Y1 - 2005
N2 - The conditional moment closure (CMC) model is applied to predict flame structures and NO formation in the moderate and intense low oxygen dilution combustion mode. The effects of oxygen concentration in a hot diluted oxidant stream are investigated in the experimental condition of Dally et al. [Proc. Combust. Inst. 29 (2002) 1147-1154]. The GRI 2.11 Mech is used for description of chemical reaction including NOx chemistry. The conditional scalar dissipation rate, which describes the effect of turbulent mixing on finite chemistry, is calculated by integrating the transport equation for probability density function (PDF). A new PDF is proposed to describe three stream mixing in terms of a single mixture fraction. The conditional mean predictions of temperature, and CO, OH, and NO mass fractions are in good agreement with measurements. The unconditional Favre mean predictions of CO and NO mass fractions are also in reasonable agreement. Upstream underprediction of OH and NO in the low oxygen concentration case may be attributed to uncertainty in low temperature reaction mechanism and mixing prediction. Differential diffusion effects are shown to be nonnegligible in the present flames. The CMC model is an attractive choice for simulation of MILD combustion in which conditional fluctuations of reactive scalars are small enough for first-order closure of conditional mean reaction rates to remain valid.
AB - The conditional moment closure (CMC) model is applied to predict flame structures and NO formation in the moderate and intense low oxygen dilution combustion mode. The effects of oxygen concentration in a hot diluted oxidant stream are investigated in the experimental condition of Dally et al. [Proc. Combust. Inst. 29 (2002) 1147-1154]. The GRI 2.11 Mech is used for description of chemical reaction including NOx chemistry. The conditional scalar dissipation rate, which describes the effect of turbulent mixing on finite chemistry, is calculated by integrating the transport equation for probability density function (PDF). A new PDF is proposed to describe three stream mixing in terms of a single mixture fraction. The conditional mean predictions of temperature, and CO, OH, and NO mass fractions are in good agreement with measurements. The unconditional Favre mean predictions of CO and NO mass fractions are also in reasonable agreement. Upstream underprediction of OH and NO in the low oxygen concentration case may be attributed to uncertainty in low temperature reaction mechanism and mixing prediction. Differential diffusion effects are shown to be nonnegligible in the present flames. The CMC model is an attractive choice for simulation of MILD combustion in which conditional fluctuations of reactive scalars are small enough for first-order closure of conditional mean reaction rates to remain valid.
KW - CMC
KW - MILD combustion
KW - Turbulent nonpremixed flames
UR - http://www.scopus.com/inward/record.url?scp=84964199526&partnerID=8YFLogxK
U2 - 10.1016/j.proci.2004.08.161
DO - 10.1016/j.proci.2004.08.161
M3 - Article
AN - SCOPUS:84964199526
SN - 1540-7489
VL - 30
SP - 751
EP - 757
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 1
T2 - 30th International Symposium on Combustion
Y2 - 25 July 2004 through 30 July 2004
ER -