Temporal evolution of turbulence/chemistry interactions in lifted, turbulent-jet flames
- Sandia National Labs., Livermore, CA (United States)
- Altex Technologies Corp., Santa Clara, CA (United States)
Flame ignition, extinction and reignition that control flame stability are time dependent. Two-pulse images of the instantaneous CH/CH{sub 4} distributions, with a variable time delay between images, were used to study the temporal evolution of turbulence/chemistry interactions in lifted, turbulent CH{sub 4}-jet flames. The jet exit velocity was 21 m/s (jet exit Reynolds number 7,000). The results emphasize interactions between turbulence structure and the flame that lead to large fluctuations in experimental flame lift-off height. The results show that the flame envelope curves around semi-organized, large-scale vortical structures formed along the periphery of the jet. Interactions between these vortical structures and the flame cause excessive stretch that leads to local flame extinction. Extinction occurs on both the downstream edges of the structures and on the upstream sides. Once the flame is extinguished by a vortical structure, the flame stabilization point can be carried significant distances downstream by the vortex. The return to an upstream stabilization location occurs through turbulent premixed flame propagation. The images show upstream propagation of the flame within the image plane. Evidence also exists for the importance of flame propagation in the azimuthal direction normal to the image plane.
- Research Organization:
- Sandia National Labs., Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); Gas Research Inst., Chicago, IL (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10193278
- Report Number(s):
- SAND-94-8730C; CONF-940711-18; ON: DE95002481
- Resource Relation:
- Conference: 25. international symposium on combustion,Irvine, CA (United States),31 Jul - 5 Aug 1994; Other Information: PBD: [1994]
- Country of Publication:
- United States
- Language:
- English
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