Simultaneous optical measurement of soot volume fraction and temperature in premixed flames
- National Inst. of Standards and Technology, Gaithersburg, MD (United States). Building and Fire Research
The performance of a three-wavelength optical probe technique for measuring soot volume fraction and temperature was assessed by conducting experiments in the homogeneous environment of a premixed flame. Using a premixed ethylene/air flame, the temperatures and soot volume fractions (f[sub va], based on absorption measurements at 633 nm and f[sub ve], based on emission measurements at 900 nm and 1,000 nm) were compared with previously reported results. Although the temperatures and mean soot volume fractions compared favorably, the discrepancy between f[sub va] and f[sub ve] prompted new measurements to evaluate the importance of source wavelength on the f[sub va] measurements, scattering by soot particles, light absorption by large molecules and the use of different indices of refraction reported in the literature. The experiments on the degree of soot scattering and light absorption by large molecules indicated that these effects cannot reconcile the observed discrepancy in the soot volume fractions. The measured soot volume fractions were, however, sensitive to the absorption constant and therefore varied significantly when different sets of refractive indices were used. Furthermore, the agreement between f[sub va] and f[sub ve] was improved when extinction measurements were performed with longer wavelength light sources. Isokinetic sampling experiments were also performed to compare with the optically-measured soot volumes fractions. This technique does not rely on the refractive indices of soot and therefore provides an independent measure of the soot volume fraction. The soot volume fractions measured using this technique compared favorably with the optically measured values (calculated using various indices of refraction).
- OSTI ID:
- 6963501
- Journal Information:
- Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 99:1; ISSN CBFMAO; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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