Two-Dimensional Soot Pyrometry with a Color Digital Camera

The potential application of a relatively low-cost, color digital camera, for use as a three-color optical pyrometer is investigated with the goal of measuring soot temperatures within a flame. The use of the built-in color filter array (CFA) of the digital camera allows for two-dimensional imaging of flame emission at the wavelengths of the color filters. The image data provide pixel-by-pixel spectral and spatial information, which is then used to calculate the two-dimensional flame temperatures. The filter profiles of the CFA were characterized to provide a calibration for the two-color method used to calculate the temperatures. Images were taken of sooting, axisymmetric laminar ethylene flames, and the two-dimensional temperature field was calculated. Comparisons are made to temperature and soot distributions provided by a recent set of calculations. It is demonstrated that a consumer digital camera can be used effectively as a multi-wavelength pyrometer. Future work will include improved characterization of the camera and an independent direct blackbody calibration in order to provide temperatures with respect to a known reference point.