Experimental and theoretical study of a premixed vibrating flame

Journal Article · Fri Jan 31 23:00:00 EST 1992 · Combustion and Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(92)90049-U· OSTI ID:5497748

Baillot, F; Durox, D; Prud'Homme, R ^[1]

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1. Lab. d'Aerothermique du CNRS, F-92190 Meudon (FR)

This paper reports on an experimental study of vibrating flames above a cylindrical burner which has been conducted in order to examine some of the fundamental characteristics of the flow perturbations-combustion interaction. Here the perturbation chosen is a space-time sinusoidal flow velocity. The vibrational nature of the flow has been studied with the without the flame, using a LDV setup and a tomography system. The prevalent kinematic phenomenon is an effect of flow pumping-indeed the velocity perturbation propagates along the vertical axis nearly at the mean flow velocity. A laminar flame in such a flow modulation ({lt}200 Hz) responds with a periodic distortion around its steady, almost conical, configuration. The oscillation is the same frequency as that produced by the flow pumping. The deformation and the kinematics of the flame, studied by the means of a tomography system and a photographic record, are characterized by the height, the length, the area, and at the top by the flapping, the absolute speed, the thickness of the thermodiffusive zone, and the normal burning speed. In particular, the burning speed evolves globally between 0.5 and 2 times the laminar burning speed measured at the top of the reference steady flame. The area variations evolve from 11% to 25%, for the RMS intensity of the velocity fluctuations well below 10%. Nevertheless over a cycle the mean area is approximately equal to that of the laminar steady reference flame. On average the instantaneous stretching effects are negligible on the front structure, in spite of the presence of large instantaneous effects like at the top. An analytical model, based on small disturbances theory and a constant burning speed, shows that the space-time front deformation results from waves originating at the flame base towards it upper limit. a comparison between theoretical and experimental results is a good agreement.

• OSTI ID: 5497748
• Journal Information: Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 88:2; ISSN CBFMA; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
BURNERS
CONFIGURATION
COUPLING
CYLINDRICAL CONFIGURATION
DIAGNOSTIC TECHNIQUES
DISTURBANCES
FLAMES
FLUCTUATIONS
FLUID FLOW
LAMINAR FLOW
MATHEMATICAL MODELS
MIXING
MODULATION
SPACE-TIME
TOMOGRAPHY
VARIATIONS
VELOCITY