Numerical simulation and flight experiment on oscillating lifted flames in coflow jets with gravity level variation
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)
- Division of Mechanical Science, Hokkaido University, Sapporo 060-8628 (Japan)
Characteristics of oscillating lifted flames have been investigated numerically and experimentally by varying the gravity level in coflow jets with propane fuel highly diluted with nitrogen. The results showed that the oscillation amplitude and frequency increased with gravity level. As the gravity level decreased, the oscillation ceased and stationary lifted flames were stabilized when the gravity level became smaller than a critical value. A flame blowout occurred at high gravity levels. The reason for this limited range of oscillation has been analyzed by considering the local characteristics of the propagation speed of tribrachial (triple) flame and axial velocity at the edges of lifted flames. Considerations of the maximum and minimum values of these two components with gravity level during the flame edge oscillation could successfully explain the lower bounds of oscillation accounting for the influences of buoyancy and flame curvature. The blowout at high gravity levels can be explained by the effect of buoyancies on burnt gas and on propane fuel in such a way that the stoichiometric contour near the flame zone became detached from the contour near the nozzle. Finally, the experiments by varying gravity level through the parabolic flights of an aircraft substantiated the overall behavior of the oscillating lifted flames. (author)
- OSTI ID:
- 20727301
- Journal Information:
- Combustion and Flame, Vol. 145, Issue 1-2; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
Similar Records
Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature
Electric fields effect on liftoff and blowoff of nonpremixed laminar jet flames in a coflow