직류전기장이 인가된 층류제트화염에서 물질-열 확산과 부력에 의한 진동비교에 관한 연구
A Comparative Study Between Diffusive-thermal and Buoyancy-driven Self-excitations in Laminar Free Jet Flames with Applied DC Electric Fields
1
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
Experimental study on comparison of diffusive-thermal self-excitation with buoyancy-driven one due to accumulation of partially premixed, preheated mixture in front of edge flame was conducted in horizontally and vertically injected laminar free-jet flames with an applied DC electric field of -10 kV. The application of horizontal injection method with the DC electric field to jet flames was experimentally designed to suppress heat-loss-induced self-excitation and thereby to highlight the definite difference between both diffusive-thermal and buoyancy-driven self-excitations with the same order of O(1.0 Hz), in that diffusive-thermal self-excitation has not been so far found experimentally in laminar jet flames. Flame stability maps in vertically and horizontally injected jet flames are presented. The distinct modes of individual self-excitation are shown to be well described by their own phase diagrams. The results show that buoyancy-driven self-excitation due to the accumulation of partially premixed, preheated mixtures in front of edge flame is branched from the buoyancy-induced self-excitation with O(10 Hz) due to a flame flicker. Once the buoyancy-driven self-excitation appears, it suppresses buoyancy-induced as well as diffusive-thermal self-excitation. The key characteristics for individual self-excitation are discussed and their functional dependencies of Strouhal number upon related physical parameters are also presented.
Abstract
Experimental study on comparison of diffusive-thermal self-excitation with buoyancy-driven one due to accumulation of partially premixed, preheated mixture in front of edge flame was conducted in horizontally and vertically injected laminar free-jet flames with an applied DC electric field of -10 kV. The application of horizontal injection method with the DC electric field to jet flames was experimentally designed to suppress heat-loss-induced self-excitation and thereby to highlight the definite difference between both diffusive-thermal and buoyancy-driven self-excitations with the same order of O(1.0 Hz), in that diffusive-thermal self-excitation has not been so far found experimentally in laminar jet flames. Flame stability maps in vertically and horizontally injected jet flames are presented. The distinct modes of individual self-excitation are shown to be well described by their own phase diagrams. The results show that buoyancy-driven self-excitation due to the accumulation of partially premixed, preheated mixtures in front of edge flame is branched from the buoyancy-induced self-excitation with O(10 Hz) due to a flame flicker. Once the buoyancy-driven self-excitation appears, it suppresses buoyancy-induced as well as diffusive-thermal self-excitation. The key characteristics for individual self-excitation are discussed and their functional dependencies of Strouhal number upon related physical parameters are also presented.
참고문헌 (15)
- S. H. Won, "Lifted flames stabilization in developing and developed regions of coflow jets for highly diluted propane", Proc. Combust. Inst., 28, pp.2093~2099 (2000)
- S. H. Won, "Normal and microgravity experiment of oscillating lifted flames in coflow", Proc. Combust. Inst., 29, pp.37~44 (2002)
- 박정, "Self-excitation in laminar lifted free-jet propane flames diluted with nitrogen", COMBUSTION AND FLAME, 158(10), pp.1960~1969, ELSEVIER SCIENCE INC
- M. Füri, "Non-premixed jet flame pulsations near extinction", Proc. Combust. Inst., 28, pp.831~838 (2000)
- Kurdyumov, V., "Stabilization and onset of oscillation of an edge-flame in the nearwake of a fuel injector", Combust. Inst., 31, pp.909~917 (2007)
- Kurdyumov, V., "Dynamics of an edge flame in a mixing layer", Combust. Flame, 139, pp.329~339 (2004)
- Kurdyumov, V., "Radiation losses as a driving mechanism for flame oscillations", Proc. Combust. Inst., 29, pp.45~52 (2002)
- Kurdyumov, V., "The porousplug burner:Flame stabilization, onset of oscillation, and restabilization", Proc. Combust. Flame, 153, pp.105~118 (2008)
- Lawton, J., "Electrical Aspects of Combustion, Vol. 14", pp.283~284 (1970), Clarendon Press
- Lee, S. M., "Effect of Electric Fields on the Liftoff of Nonpremixed Turbulent Jet Flames", IEEE Trans. Plasma Sci., 33, pp.1703~1709 (2005)
- Won, S. H., "Effect of electric fields on reattachment and propagation speed of tribrachial flames in laminar coflow jets", Proc. Combust. Inst., 31, pp.963~970 (2007)
- Won, S. H., "Effect of electric fields on the propagation speed of tribrachial flames in coflow jets", Combust. Flame, 152, pp.496~506 (2008)
- Cetegen, B. M., "Experiments on the oscillatory behavior of buoyant plumes of helium and helium-air mixture", Phys. Fluids, 8, pp.2974~2984 (1996)
- Lee, B. J., "Stabilization of lifted tribrachial flames in a laminar nonpremixed jet", Combust. Flame, 109, pp.163~172 (1997)
- 김성초, "Edge flame instability in low-strain-rate counterflow diffusion flames", COMBUSTION AND FLAME, 146, pp.612~619, ELSEVIER SCIENCE INC