A tomographic study of premixed turbulent stagnation point flames

Conference · Sun Oct 01 04:00:00 EDT 1989

OSTI ID:5372256

Shepherd, I. G.; Cheng, R. K.; Goix, P. ^[1]

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1. Lawrence Berkeley Lab., CA (USA)

The high speed tomographic technique has been used to study premixed flame propagation in stagnation flow stabilized flames. Studies are performed on CH4/Air and C2H4/Air flames with equivalence ratios ranging from 0.75 to 1.0. The gas velocity at the nozzle exit is 5 m/s, the turbulence intensity is varied from 5% to 7% and the turbulence Reynolds number is 70. The light source is a copper vapor laser which produces 20ns, 5 mJ pulses at a 4KHz repetition rate. Cylindrical lenses transform the 38 mm circular laser beam to a sheet 50 mm high and 0.6 mm thick. A high speed Fastax camera is used to record the tomographic images. The films are digitized and the flame front extracted from the images by a thresholding technique. A fractal analysis was performed on the flame boundaries in order to characterize the flame geometry and provide an estimate of the flame surface area. The flame area increase was found to give a reasonable estimate of the burning rate when compared with other methods if the effects of flow tube divergence were considered. Characteristic wrinkle sizes were found to be much larger than the length scales of the turbulence in the reactant stream. 8 refs., 5 figs., 2 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• Sponsoring Organization: DOD; DOE/ER
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5372256
• Report Number(s): LBL-27904; CONF-8910289--2; ON: DE90002462; CNN: F-44620-76-C-0083
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
ALKENES
COMBUSTION PROPERTIES
DIAGNOSTIC TECHNIQUES
FLAME PROPAGATION
HYDROCARBONS
MATHEMATICAL MODELS
METHANE
NOZZLES
ORGANIC COMPOUNDS
STAGNATION POINT
TOMOGRAPHY
TURBULENCE