Novel soot volume fraction measurement through ratio-
           pyrometry and absolute light calibration
                          Bin Ma and Marshall B. Long
                 Yale University, 15 Prospect St, New Haven, CT, USA
                                   bin.ma@yale.edu

        Novel ratio pyrometry and absolute light calibration methods have been
developed to obtain soot temperature and volume fraction in axisymmetric flames. A
consumer digital single lens reflex camera has been fully characterized and utilized
as a pyrometer. The incandescence from soot was imaged at the three wavelengths
of the camera’s color filter array (CFA). Temperatures were calculated by two-color
ratio pyrometry using a lookup table approach. While temperatures can be extracted
from color ratios, soot volume fraction requires an absolute light calibration of the
detector. The absolute light intensity calibration was provided by a flame-heated S-
type thermocouple. The spectral emissivity of S-type thermocouple wires (Pt and Pt-
10% Rh) was measured in the visible range. The measured spectral emissivity,
temperature, and diameter of the heated thermocouple wires allow them to serve as
a light source with spectral radiance that can be calculated by Planck’s law. Soot
volume fraction measurements were carried out on four different flames with varying
levels of soot loading. The results have been compared with previous LII results and
excellent agreement has been achieved.




             5th international workshop on Laser-Induced Incandescence
              May 9-11, 2012, Palais des Congrès, Le Touquet, France