TY - JOUR
T1 - Three-dimensional numerical simulations of cellular jet diffusion flames
AU - Frouzakis, C. E.
AU - Tomboulides, A. G.
AU - Papas, P.
AU - Fischer, P. F.
AU - Rais, R. M.
AU - Monkewitz, P. A.
AU - Boulouchos, K.
N1 - Funding Information:
The financial support from the Swiss Office of Energy (BfE) for CEF and KB, and the Swiss National Science Foundation (Grants NF20-61887.00 and NF-57100.99) for PP and RMR, a SNSF grant (number PIOI2-103091) for AGT, and from the U.S. Department of Energy (Contract W-31-109-Eng-38) for PFF is gratefully acknowledged. The authors are also grateful to Prof. M. Matalon for many fruitful discussions.
Publisher Copyright:
© 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
PY - 2005
Y1 - 2005
N2 - Recent experimental investigations have demonstrated that the appearance of particular cellular states in circular non-premixed jet flames significantly depends on a number of parameters, including the initial mixture strength, reactant Lewis numbers, and proximity to the extinction limit (Damköhler number). For CO2-diluted H2/O2 jet diffusion flames, these studies have shown that a variety of different cellular patterns or states can form. For given fuel and oxidizer compositions, several preferred states were found to co-exist, and the particular state realized was determined by the initial conditions. To elucidate the dynamics of cellular instabilities, circular non-premixed jet flames are modeled with a combination of three-dimensional numerical simulation and linear stability analysis (LSA). In both formulations, chemistry is described by a single-step, finite-rate reaction, and different reactant Lewis numbers and molecular weights are specified. The three-dimensional numerical simulations show that different cellular flames can be obtained close to extinction and that different states co-exist for the same parameter values. Similar to the experiments, the behavior of the cell structures is sensitive to (numerical) noise. During the transient blow-off process, the flame undergoes transitions to structures with different number of cells, while the flame edge close to the nozzle oscillates in the streamwise direction. For conditions similar to the experiments discussed, the LSA results reveal various cellular instabilities, typically with azimuthal wavenumber m = 1-6. Consistent with previous theoretical work, the propensity for the cellular instabilities is shown to increase with decreasing reactant Lewis number and Damköhler number.
AB - Recent experimental investigations have demonstrated that the appearance of particular cellular states in circular non-premixed jet flames significantly depends on a number of parameters, including the initial mixture strength, reactant Lewis numbers, and proximity to the extinction limit (Damköhler number). For CO2-diluted H2/O2 jet diffusion flames, these studies have shown that a variety of different cellular patterns or states can form. For given fuel and oxidizer compositions, several preferred states were found to co-exist, and the particular state realized was determined by the initial conditions. To elucidate the dynamics of cellular instabilities, circular non-premixed jet flames are modeled with a combination of three-dimensional numerical simulation and linear stability analysis (LSA). In both formulations, chemistry is described by a single-step, finite-rate reaction, and different reactant Lewis numbers and molecular weights are specified. The three-dimensional numerical simulations show that different cellular flames can be obtained close to extinction and that different states co-exist for the same parameter values. Similar to the experiments, the behavior of the cell structures is sensitive to (numerical) noise. During the transient blow-off process, the flame undergoes transitions to structures with different number of cells, while the flame edge close to the nozzle oscillates in the streamwise direction. For conditions similar to the experiments discussed, the LSA results reveal various cellular instabilities, typically with azimuthal wavenumber m = 1-6. Consistent with previous theoretical work, the propensity for the cellular instabilities is shown to increase with decreasing reactant Lewis number and Damköhler number.
KW - Cellular flame
KW - Diffusion flame instability
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U2 - 10.1016/j.proci.2004.08.087
DO - 10.1016/j.proci.2004.08.087
M3 - Conference article
AN - SCOPUS:84964300618
SN - 1540-7489
VL - 30
SP - 185
EP - 192
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 -