Structure and propagation of premixed flame in nozzle-generated counterflow

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(97)89633-2· OSTI ID:543420

Chao, B H ^[1]; Egolfopoulos, F N ^[2]; Law, C K ^[3]

---

1. Univ. of Hawaii, Honolulu, HI (United States). Dept. of Mechanical Engineering
2. Univ. of Southern California, Los Angeles, CA (United States). Dept. of Mechanical Engineering
3. Princeton Univ., NJ (United States). Dept. of Mechanical and Aerospace Engineering

The accuracy of the counterflow, twin-flame technique for the determination of laminar flame speeds was examined analytically, numerically and experimentally. The analysis was conducted by using multiple-expansion, large activation energy asymptotics, while the numerical simulation incorporated detailed chemistry and transport. In both approaches the solutions were obtained in a finite domain and with plug flow boundary conditions in order to better simulate the actual experiments. Results show that linear extrapolation of the minimum velocity to zero stretch overestimates the true laminar flame speed. This overestimate, however, can be reduced by using larger nozzle separation distances. The theoretical results were further confirmed by experimental measurements for methane/air flames with various stoichiometries and nozzle separation distances. The numerical and experimental results indicate that for atmospheric methane/air flames, nozzle separation distances in excess of about 2 cm yield laminar flame speeds obtained by linear extrapolation accurate to within the uncertainty range of the experiment. The results obtained herein thus provide further support for the viability of the counterflow technique, when the influence of the nozzle separation distance is properly accounted for. The viability of an alternate technique for the determination of laminar flame speeds, based on the variation of flow velocity at a constant temperature near the upstream boundary of the flame with stretch, was also theoretically investigated.

• OSTI ID: 543420
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 4 Vol. 109; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
COMBUSTION KINETICS
COUNTERFLOW SYSTEMS
DIAGNOSTIC TECHNIQUES
FLAME PROPAGATION
FLAMES
MATHEMATICAL MODELS
METHANE
MORPHOLOGY