Imaging of flame behavior in flickering methane/air diffusion flames

During this study, flow visualization through the use of imaging provided visual data of the events that occurred as the flame oscillated. Imaging was performed in two different ways: 1) the first method was phase-locked imaging to capture a detailed history by simply advancing the phase angle during each image capture, 2) the second method involved high-speed imaging to gather visual image data of a natural or forced oscillating flame. For visualization, two items were considered. The first one was the shape of the flame envelope as it evolved during one oscillation cycle. From the data gathered, it was confirmed that the flame stretched in the vertical direction before quenching in the region near its center. The second consideration was imaging of the oxidizer (air) in the region immediately outside the flame. This was done by imaging the laser light reflected from particles seeded into the flow, which revealed formation of vortical structures in those regions where quenching had occurred. It was noted that quenching took place primarily by the entrainment of fresh non-reacting air into the flame. The quenching process was in turn responsible for the oscillatory behavior.

[1]  William M. Pitts,et al.  Flow characterization of flickering methane/air diffusion flames using particle image velocimetry , 2002 .

[2]  W. M. Roquemore,et al.  Effect of nonunity Lewis number and finite-rate chemistry on the dynamics of a hydrogen-air jet diffusion flame , 1994 .

[3]  Yuji Nakamura,et al.  Imaging and diagnostics of turbulent methane-air premixed flames by acetone-OH simultaneous PLIF , 2008, J. Vis..

[4]  Kenji Amagai,et al.  Diffusion flames and their flickering motions related with Froude numbers under various gravity levels , 2000 .

[5]  V. R. Katta,et al.  Role of inner and outer structures in transitional jet diffusion flame , 1993 .

[6]  A. Melling.  Tracer particles and seeding for particle image velocimetry , 1997 .

[7]  Suk Ho Chung,et al.  Several applications of laser diagnostics for visualization of combustion phenomena , 2003, J. Vis..

[8]  U. Hegde,et al.  Flame radiation and acoustic intensity measurements in acoustically excited diffusion flames , 1993 .

[9]  William M. Pitts,et al.  Greatly enhanced soot scattering in flickering CH4/Air diffusion flames , 1993 .

[10]  Yong Yan,et al.  On-line flicker measurement of gaseous flames by image processing and spectral analysis , 1999 .

[11]  Flame flickering frequency on a rotating Bunsen burner , 2007 .

[12]  M. Schreiber,et al.  Instability of buoyant diffusion flames , 1996 .

[13]  Takashi Kashiwagi,et al.  An experimental investigation of the pulsation frequency of flames , 1992 .

[14]  M. Arai,et al.  Gravity effects on stability and flickering motion of diffusion flames , 1999 .

[15]  Baki M. Cetegen,et al.  Experiments on the periodic instability of buoyant plumes and pool fires , 1993 .

[16]  I. Puri,et al.  Gravity effects on triple flames: Flame structure and flow instability , 1999 .

[17]  Gang Lu,et al.  Three-dimensional visualization and quantitative characterization of gaseous flames , 2002 .

[18]  Coherent and random structure in reacting jets , 1990 .

[19]  M. Bahadori,et al.  Functional dependence of flame flicker on gravitational level , 2001 .

[20]  J. Buckmaster,et al.  The infinite candle and its stability—A paradigm for flickering diffusion flames , 1988 .

[21]  N. Fujisawa,et al.  Simultaneous measurement of three-dimensional flame contour and velocity field for characterizing the flickering motion of a dilute hydrogen flame , 2007 .

[22]  J. Whitelaw,et al.  Aspects of oscillating flames , 1998 .

[23]  W. Pitts.  Thin-filament pyrometry in flickering laminar diffusion flames , 1996 .