Sensitivity and relative error analyses of soot temperature and volume fraction determined by two-color LII

Abstract

The sensitivity and relative sensitivity of soot temperature and soot volume fraction inferred from the two-color laser-induced incandescence technique to different variables were systematically investigated to quantitatively understand how the detection wavelengths affect the behavior of the detection system. The effects of signal shot noises on the derived soot temperature and soot volume fraction were also analyzed. The detection wavelengths are in general between about 400 nm for the lower band and near infrared for the upper one. Numerical calculations were conducted for seven detection wavelength selections commonly used in two-color laser-induced incandescence experiments reported in the literature. To achieve a better accuracy for soot temperature and volume fraction measurements, it is desirable to use a shorter lower detection wavelength and a longer upper detection wavelength in the spectral range of about 400 nm to near infrared. The lower detection wavelength has a stronger impact on the detection system performance than the upper one. The sensitivity and shot noise analyses are valuable tools to assess the relative performance of different detection wavelengths and should be used in combination with other considerations to design an optimal detection system in a two-color laser-induced incandescence experiment.