Abstract

A technique is proposed and demonstrated for measuring combustion temperatures using two-line laser-saturated fluorescence. The rotational temperature of OH is determined by saturating two different rotational transitions in the (0,0) band of the A²∑⁺–X²Π electronic system and detecting fluorescence emission which originates from the laser-pumped upper rotational levels. Temperature is calculated from the ratio of the fluorescence intensities for the two different excitation–emission pairs. The method is demonstrated by measuring temperature profiles in subatmospheric H₂/O₂/Ar flat flames. Temperatures measured by two-line saturated fluorescence are compared with temperatures measured by coated thermocouples and OH absorption and with predictions from an elementary chemical kinetics code. The temperatures measured by the two-line fluorescence technique are accurate to 3–5% and exhibit low random error.

© 1982 Optical Society of America

OH rotational temperature from two-line laser-excited fluorescence

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