Soot and thin-filament pyrometry using a color digital camera

Abstract

A simple and compact temperature and soot volume fraction diagnostic technique based on ratio pyrometry has been studied. Two different consumer digital single lens reflex cameras were evaluated for use as pyrometers. The incandescence from soot and a SiC filament was imaged at the three wavelengths of each camera’s color filter array (CFA). After characterization of the detector’s signal response curves, temperatures were calculated by two-color ratio pyrometry using a lookup table approach. A SiC filament with known emissivity was shown to provide an absolute light intensity calibration, which further allows the soot volume fraction to be determined. Measurements were carried out on four different flames with varying levels of soot loading. The filament-derived gas temperature and soot temperature measurements have been compared with computational results and overall good agreement has been shown. Soot volume fraction measurements have been compared with previous LII results, with excellent agreement for both cameras tested.