Spatially and temporally resolved temperature measurements in counterflow flames using a single interband cascade laser

Spatially and temporally resolved temperatures are measured in counterflow diffusion flames with a tunable diode laser absorption spectroscopy (TDLAS) technique based on direct absorption of CO2 near 4.2 mu m. An important aspect of the present work is the reduction of the beam diameter to around 150 mu m, thus providing high spatial resolution that is necessary to resolve the high axial temperature gradient in counterflow flames. The temperature non-uniformity was taken into account through both hyperspectral tomography and the multiline technique with profile fitting, with the latter one being capable of providing temporally resolved data. The proposed methods were used to measure four counterflow flames with peak temperature ranging from 1654 to 2720 K, including both non-sooting and sooting ones. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement