A calibration-free two-dimensional spectral soot emission platform for temperature and soot measurements

Abstract

A simple and cost-effective temperature and soot volume fraction measurement technique that does not rely on spectral or absolute irradiance calibration is developed. The technique is based on a three-sensor CMOS camera, where the broadband sensitivity of RGB sensors were narrowed down to representative wavelengths using a tri-bandpass filter. A telecentric imaging lens was used to improve the accuracy of the tomographic deconvolution of the axisymmetrical ethylene laminar diffusion flames stabilized on a co-flow burner. Temperature and soot concentration measurements have been compared with results previously reported from the same burner. Good agreement for temperature measurements and excellent agreement for soot concentration measurements have been shown. Additionally, to demonstrate the dynamic range of the system, two-dimensional temperature and soot volume fraction fields were measured for four cases of dilution corresponding to various soot loadings. As the dilution rate was increased, the peak soot volume fraction was drastically reduced and temperatures were increased in accordance with the reduced dissipative heat losses from broadband soot radiation.