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Laboratory Apparatus for the Measurement of Optical Extinction Coefficients of Postflame Soot in the Infrared.


pdf icon Laboratory Apparatus for the Measurement of Optical Extinction Coefficients of Postflame Soot in the Infrared. (108 K)
Widmann, J. F.; Yang, J. C.; Bundy, M.; Tsai, B. K.; Mulholland, G. W.

Review of Scientific Instruments, Vol. 74, No. 2, 938-944, February 2003.

Keywords:

soot; radiative heat transfer; smoke

Abstract:

An experimental apparatus for the measurement of optical extinction coefficients of postflame soot aerosol in the infrared region of the electromagnetic spectrum is presented. Reproducible soot aerosol is generated using a laminar diffusion burner, and the mass concentration of the aerosol is determined gravimetrically. The instrument, which utilizes an infrared spectrograph for the extinction measurements, provides data over the wavelength range 2.55.0 mum. The infrared spectrograph, which provides a near-instantaneous measurement of the incident radiation over a range of wavelengths, is ideal for applications in which the deposition of soot over time on the optical windows can interfere with the measurement. Furthermore, the wavelength dependence of the extinction coefficient can be determined independently of the gravimetric measurements, which represents the dominant source of uncertainty in the measurement of the mass specific extinction coefficient. The spectrograph reported herein has been characterized using a well-characterized sodium heat pipe blackbody, and the responsivity of the instrument has been quantified as a function of wavelength.