Assessment of single-shot temperature measurements by thermally-assisted OH PLIF using excitation in the A2Σ+–X2Π (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 A2Σ+–X2Π (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 Q2(7), Q1(8), R1(14), and P1(2). It is found to be the most efficient for Q1(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.