Assessment of single-shot temperature measurements by thermally-assisted OH PLIF using excitation in the A(2)Sigma(+)-X-2 Pi(1-0) band

The present paper reports on the assessment of single-shot 2D temperature measurements by thermally assisted OH PLIF for the excitation of the A(2)Sigma(+)-X-2 Pi (1-0) band. The temperature sensitivity of the ratio between the emission intensity of the (2-0) band and (0-0), (1-1) bands is numerically tested by using a LASKIN software package for the transitions Q(2)(7), Q(1)(8), R-1(14), and P-1(2). It is found to be the most efficient for Q(1)(8), for which the ratio almost linearly depends on the temperature in the range of 1200-2200 K. Fluorescence quenching by oxygen has a minor effect on the results. The capability of the temperature measurements by the thermally assisted OH PLIF has been experimentally tested for a laminar premixed methane/air flame based on comparison with the results of two-line and line-scanning PLIF thermometry. The method is also applied for a partially premixed turbulent swirling flame in a model gas-turbine combustor. The method allows to detect hot regions in turbulent flames. (c) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.