The accuracy and precision of multi-line NO-LIF thermometry in a wide range of pressures and temperatures

An automated spectral fitting algorithm (named Thermo NO-LIF) designed for the extraction of temperature information from experimental NO-LIF spectra is presented and analysed. With the aid of the Thermo NO-LIF, the high-accuracy (0.5%) of multi-line NO-LIF thermometry are demonstrated in the burnt-gases region of a near-adiabatic Bunsen-type premixed flame. The results are compared with the temperature measured using N-2 spontaneous Raman scattering (SRS). The current study also applies and analyses the algorithm and the thermometry technique in a premixed flat-flame under various sub-atmospheric pressures. The results suggest that choosing a long excitation scan range with as few overlapping lines as possible can maximise the performance of the multi-line NO-LIF thermometry. The uncertainty arising from the overlapping lines is especially crucial at atmospheric pressure. Additionally, the current study compares the performance of multi-line NO-LIF thermometry using narrowband and broadband lasers. Thermo NO-LIF is available to anyone interested in applying multi-line NO-LIF thermometry. (c) 2020 Elsevier Ltd. All rights reserved.