Optical measurements of soot and temperature profiles in premixed propane-oxygen flames
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 to 632.8 nm and 457.9 nm to 632.8 nm wavelength combinations, and extinction/scattering using 514.5 nm light. The flames wre fuel-rich (equivalence ratios from 2.1 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 infrared radiometry. 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 ratios up to 0.95.
- Research Organization:
- National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center
- OSTI ID:
- 5564706
- Report Number(s):
- N-88-29997; NASA-TM--101343; E--4363; NAS--1.15:101343; CONF-881120--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Optical measurements of soot in premixed flames
Optical measurements of soot formation in premixed flames
Related Subjects
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
CHEMICAL REACTIONS
COMBUSTION
DIAGNOSTIC TECHNIQUES
ELEMENTS
FLAMES
HYDROCARBONS
NONMETALS
OPTICAL SYSTEMS
ORGANIC COMPOUNDS
OXIDATION
OXYGEN
PARTICLE SIZE
PROPANE
SIZE
SOOT
TEMPERATURE DISTRIBUTION
THERMOCHEMICAL PROCESSES