Affiliations: Department of Mechanical Engineering, New Mexico
Institute of Mining and Technology, Socorro, NM 87801 USA. E-mail:
yilmaznadir@yahoo.com | Fire and Aerosol Sciences, Sandia National
Laboratories, Albuquerque, NM 87185 USA | Department of Mechanical Engineering, New Mexico State
University, Las Cruces, NM 88003 USA
Abstract: 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.
Keywords: High Speed Imaging, Air Entrainment, Flame Visualization, Diffusion Flame Oscillation
