Flame-vortex dynamics in an inverse partially premixed combustor: The Froude number effects

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(97)00018-7· OSTI ID:543508

Shu, Z; Aggarwal, S K; Puri, I K ^[1]; Katta, V R ^[2]

---

1. Univ. of Illinois, Chicago, IL (United States). Dept. of Mechanical Engineering
2. Innovative Scientific Solutions, Inc., Dayton, OH (United States)

In this paper, the authors report on a computational and experimental investigation of the transient combustion characteristics of an inverse partially premixed flame established by injecting a fuel-rich (CH{sub 4}-air) annular jet sandwiched between a central air jet on the inside and coflowing air on the outside. A time-dependent, axisymmetric, reacting flow model is used to simulate the flame dynamics. A global 1-step and a relatively detailed 52-step mechanism are used to model the CH{sub 4}-air chemistry. Results focus on the dynamic flame structure and flame-vortex interactions at different Froude numbers (Fr), the scaling of the flame flicker frequency, and the global comparison of experimental and computational results. Methane is converted to CO and H{sub 2} in the premixed reaction zone and these intermediate species provide fuel for the outer nonpremixed flames. Both numerical and laboratory experiments are employed to obtain a correlation between the Strouhal number (S), associated with the vortex rollup or flame flicker frequency, and the Froude number. Simulations yield a correlation S = 0.56 Fr{sup {minus}0.38}, while measurements yield S = 0.43 Fr{sup {minus}0.38}, indicating an excellent agreement, considering that the flow conditions in the numerical and laboratory experiments are only globally matched in terms of overall stoichiometry, Fr, and Reynolds number, and not with respect to burner size and jet velocity. Finally, the effects of chemical kinetics on the computed flame structure are examined. Both the time-averaged and the dynamic flame structure, including flame height, peak temperature, and flicker frequency, are found to be influenced by chemical kinetics.

• Sponsoring Organization: Gas Research Inst., Chicago, IL (United States)
• OSTI ID: 543508
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 4 Vol. 111; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
CARBON MONOXIDE
COMBUSTION KINETICS
FLAMES
FLOW MODELS
FLUID MECHANICS
HYDROGEN
METHANE
MORPHOLOGY
VORTEX FLOW