On transient flamelets and their relationship to turbulent methane-air jet flames
Conference
·
OSTI ID:10116115
- Sandia National Labs., Livermore, CA (United States)
- California Univ., Berkeley, CA (United States). Dept. of Mechanical Engineering
Laminar flame calculations are performed to investigate possible physical mechanisms for the apparent ``non-flamelet`` behavior that has been measured in turbulent methane-air jet flames. Three factors affecting the structure of methane-air diffusion flames are considered: (1) temporal variation of the scalar dissipation rate, (2) changes in the spatial profile of scalar dissipation, and (3) elimination of differential diffusion by setting all species Lewis numbers to unity. Results indicate that changes in the shape of the scalar dissipation profile and sinusoidal variation of the scalar dissipation have relatively minor effects on species mass fraction profiles. However, significant overshoot of the mass fractions of OH and CO occurs when a flamelet is subjected to a step decrease in scalar dissipation. This overshoot occurs without the flame being first pushed to the brink of extinction, and recovery of the flame to steady-state conditions is relatively slow. Significant changes in species mass fractions also occur when the Lewis numbers are set to unity. 16 refs., 6 figs.
- Research Organization:
- Sandia National Labs., Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DR00789
- OSTI ID:
- 10116115
- Report Number(s):
- SAND--91-8720; CONF-920707--15; ON: DE92006705
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800
99 GENERAL AND MISCELLANEOUS
990200
AIR
CARBON MONOXIDE
COMBUSTION
COMBUSTION, PYROLYSIS, AND HIGH-TEMPERATURE CHEMISTRY
COMPUTERIZED SIMULATION
DIFFUSION
FLAMES
HYDROXYL RADICALS
JETS
LAMINAR FLOW
MATHEMATICS AND COMPUTERS
METHANE
QUANTITY RATIO
TURBULENT FLOW
400800
99 GENERAL AND MISCELLANEOUS
990200
AIR
CARBON MONOXIDE
COMBUSTION
COMBUSTION, PYROLYSIS, AND HIGH-TEMPERATURE CHEMISTRY
COMPUTERIZED SIMULATION
DIFFUSION
FLAMES
HYDROXYL RADICALS
JETS
LAMINAR FLOW
MATHEMATICS AND COMPUTERS
METHANE
QUANTITY RATIO
TURBULENT FLOW