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Spectral Extinction Coefficients of Soot Aggregates From Turbulent Diffusion Flames.


pdf icon Spectral Extinction Coefficients of Soot Aggregates From Turbulent Diffusion Flames. (415 K)
Koylu, U. O.; Faeth, G. M.

Combustion Institute/Eastern States Section. Chemical and Physical Processes in Combustion. Proceedings. Fall Technical Meeting, 1995. October 16-18, 1995, Worcester, MA, 211-214 pp, 1995.

Sponsor:

Air Force Office of Scientific Research, Washington, DC

Keywords:

combustion; soot; aggregates; turbulent flames; diffusion flames; extinction; luminous flames; soot aggregates

Abstract:

Accurate knowledge of the spectral variation of the refractive indices of soot is necessary in order to estimate continuum radiation from luminous flames and to develop in-situ optical techniques for measuring soot properties. However, there are fairly large variations among the soot refractive indices reported in the literature, implying uncertainties about which values should be used in a particular application, see example, Tien and Lee, Chang and Charalampopoulos, and references cited therein for a complete discussion. Moreover, results regarding the effects of fuel type (H/C ratio) on soot refractive indices are also contradictory. Early work of Dalzell and Sarofim, and Lee and Tien suggested that soot refractive indices were relatively insensitive to fuel type. On the other hand, later work of Habib and Vervisch, and Charalampopoulos et al indicated significant effects of fuel type on soot refractive indices. However, Sivathanu et al recently reported that their measurements were most consistent with the values reported by Dalzell and Sarofim, while finding only a weak dependence of fuel type on soot refractive indices. In view of these observations, the main objective of the present study was to evaluate the capabilities of the soot refractive indices reported in the literature to treat the spectral extinction properties of soot aggregates, and to investigate the effect of fuel type on refractive indices.