TY - JOUR

T1 - On intrinsic oscillation in radiation-affected diffusion flames

AU - Wang, H. Y.

AU - Law, C. K.

N1 - Funding Information:
This research was supported by the Air Force Office of Scientific Research and NASA under the technical monitoring of Drs. Julian M. Tishkoff and Kurt Sacksteder, respectively. We sincerely appreciate the technical discussions with Professor John K. Bechtold of the New Jersey Institute of Technology during the course of this study.

PY - 2007

Y1 - 2007

N2 - A linear stability analysis is conducted to study the onset of near-limit flame oscillation with radiative heat loss in 1-D chambered planar flames using multi-scale activation-energy asymptotics. The oscillatory instability near the radiation-induced extinction limit at large Damköhler numbers is identified, in additional to the one near the kinetic limit at small Damköhler numbers. It is shown that radiative loss assumes a similar role as varying the thermal diffusivity of the reactants. Thus, flame oscillation near the radiative limit is still thermal-diffusive in nature although it may develop under unity Lewis numbers. The unstable range of Damköhler numbers near the radiative limit shows quite similar parametric dependence on the Lewis numbers of reactants, LeF and LeF, the stoichiometry, φ, and the radiative loss as that near the kinetic limit. They both increase monotonically with Leo and φ and increase then decrease with Lep. Increasing radiative loss extends the parameter range under which flame oscillations may develop. However, they show different dependence on the temperature difference between the supplying reactants. Unless radiative loss approaches its maximum value the system can sustain, flame oscillation near the radiative limit is only possible within a limited range of ΔT, whereas it is promoted monotonically with decreasing δT near the kinetic limit. Furthermore, while radiative loss shows small effect on the nondimensional oscillation frequency, the dimensional frequency of flame oscillations near the radiative limit can be substantially smaller than that near the kinetic limit.

AB - A linear stability analysis is conducted to study the onset of near-limit flame oscillation with radiative heat loss in 1-D chambered planar flames using multi-scale activation-energy asymptotics. The oscillatory instability near the radiation-induced extinction limit at large Damköhler numbers is identified, in additional to the one near the kinetic limit at small Damköhler numbers. It is shown that radiative loss assumes a similar role as varying the thermal diffusivity of the reactants. Thus, flame oscillation near the radiative limit is still thermal-diffusive in nature although it may develop under unity Lewis numbers. The unstable range of Damköhler numbers near the radiative limit shows quite similar parametric dependence on the Lewis numbers of reactants, LeF and LeF, the stoichiometry, φ, and the radiative loss as that near the kinetic limit. They both increase monotonically with Leo and φ and increase then decrease with Lep. Increasing radiative loss extends the parameter range under which flame oscillations may develop. However, they show different dependence on the temperature difference between the supplying reactants. Unless radiative loss approaches its maximum value the system can sustain, flame oscillation near the radiative limit is only possible within a limited range of ΔT, whereas it is promoted monotonically with decreasing δT near the kinetic limit. Furthermore, while radiative loss shows small effect on the nondimensional oscillation frequency, the dimensional frequency of flame oscillations near the radiative limit can be substantially smaller than that near the kinetic limit.

KW - Activation-energy asymptotics

KW - Diffusion flame

KW - Extinction

KW - Oscillatory instability

KW - Radiation

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U2 - 10.1016/j.proci.2006.07.183

DO - 10.1016/j.proci.2006.07.183

M3 - Conference article

AN - SCOPUS:34548724062

VL - 31 I

SP - 979

EP - 987

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

SN - 1540-7489

IS - 1

T2 - 31st International Symposium on Combustion

Y2 - 5 August 2006 through 11 August 2006

ER -