Structure of a stratified CH₄ flame with H₂ addition

Journal Article · Wed Sep 12 00:00:00 EDT 2018 · Proceedings of the Combustion Institute

DOI:https://doi.org/10.1016/j.proci.2018.06.205· OSTI ID:1497651

Schneider, Silvan ^[1]; Geyer, Dirk ^[2]; Magnotti, Gaetano ^[3]; Dunn, Matthew J. ^[4]; Barlow, Robert S. ^[5]; Dreizler, Andreas ^[1]

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1. TU Darmstadt (Germany). Dept. of Reactive Flows and Measurement Technology
2. Darmstadt Univ. of Applied Sciences (Germany)
3. King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia). Clean Combustion Research Center
4. Univ. of Sydney, NSW (Australia). The School of Aeronautical, Mechanical and Mechatronic Engineering
5. Sandia National Lab. (SNL-CA), Livermore, CA (United States). Reacting Flow Research Dept.

To explore the effect of H₂ addition (20 percent by volume) on stratified-premixed methane combustion in a turbulent flow, an experimental investigation on a new flame configuration of the Darmstadt stratified burner is conducted here. Major species concentrations and temperature are measured with high spatial resolution by 1D Raman-Rayleigh scattering. A conditioning on local equivalence ratio (range from φ = 0.45 to φ = 1.25) and local stratification is applied to the large dataset and allows to analyze the impact of H₂ addition on the flame structure. The local stratification level is determined as Δφ/ΔT at the location of maximum CO mass fraction for each instantaneous flame realization. Due to the H₂ addition, preferential diffusion of H₂ is different than in pure methane flames. In addition to diffusing out of the reaction zone where it is formed, particularly in rich conditions, H₂ also diffuses from the cold reactant mixture into the flame front. For rich conditions (φ = 1.05 to φ = 1.15) H₂ mass fractions are significantly elevated within the intermediate temperature range compared to fully-premixed laminar flame simulations. This elevation is attributed to preferential transport of H₂ into the rich flame front from adjacent even richer regions of the flow. Additionally, when the local stratification across the flame front is taken into account, it is revealed that the state-space relation of H₂ is not only a function of the local stoichiometry but also the local stratification level. In these flames H₂ is the only major species showing sensitivity of the state-space relation to an equivalence ratio gradient across the flame front.

• Research Organization: Darmstadt Univ. of Applied Sciences (Germany); Sandia National Lab. (SNL-CA), Livermore, CA (United States); TU Darmstadt (Germany)
• Sponsoring Organization: German Research Foundation (DFG); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: NA0003525
• OSTI ID: 1497651
• Report Number(s): SAND--2017-13162J; 672180
• Journal Information: Proceedings of the Combustion Institute, Journal Name: Proceedings of the Combustion Institute Journal Issue: 2 Vol. 37; ISSN 1540-7489
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
42 ENGINEERING
H2 addition
Raman/Rayleigh scattering
multiple conditioned data analysis
stratified flames
turbulent combustion