Optical measurements of soot in premixed flames

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7071290

Lyons, V J

Two laser diagnostic techniques were used to measure soot volume fractions, number densities and soot particle radii in premixed propane/oxygen flat flames. The two techniques used were two-wavelength extinction, using 514.5 nm-632.8 nm and 457.9 nm-632.8 nm wavelength combinations, and extinction/scattering using 514.5 nm light. The flames were fuel-rich (equivalence ratios from 1.8 to 2.8) and had cold gas velocities varying from 3.4 to 5.5 cm/s. Measurements were made at various heights above the sintered-bronze, water-cooled flat flame burner with the equivalence ratio and cold gas velocity fixed. Also, measurements were made at a fixed height above the burner and fixed cold gas velocity while varying the equivalence ratio. Both laser techniques are based on the same underlying assumptions of particle size distribution and soot optical properties. Full Mie theory was used to determine the extinction coefficients, K{sub ext}, and the scattering efficiencies, Q{sub vv}. Temperature measurements in the flames were made using infra-red radiometry and fine-wire thermocouples. Good agreement between the two techniques in terms of soot particle radii, number density and volume fraction was found for intensity ratios (I/I{sub o}) between 0.1 and 0.8. For intensity ratios higher, or lower than this range, the differences in extinction coefficients at the wavelengths chosen for the two-wavelength method are too small to give accurate results for comparing particle radii and number densities. However, when comparing only soot volume fractions, the agreement between the two techniques continued to be good for intensity rations up to 0.95.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 7071290
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
BURNERS
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
ELEMENTS
EQUIPMENT
FLAMES
FLOW RATE
FLUID FLOW
FUEL-AIR RATIO
GAS FLOW
HYDROCARBONS
INHIBITION
KINETICS
LASERS
MEASURING METHODS
MONITORING
NONMETALS
OPTICAL EQUIPMENT
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
OXYGEN
PARTICLE SIZE
PHYSICAL PROPERTIES
PROPANE
QUANTITY RATIO
REACTION KINETICS
SIZE
SOOT
TEMPERATURE MEASUREMENT