A new method for flame temperature measurement has been developed involving measurement of radiation, emitted by flames, in a narrow wavelength interval within the ultraviolet OH emission band. The mean value of flame emissivity within the wavelength interval is evaluated by measurement of mean flame transmission for a continuous spectrum source. The method requires that the wavelength interval studied be so narrow that the emission of the source used for transmission measurement and that of a blackbody at flame temperature both be approximately constant over the interval.
The method has been tested on steady flames over temperature ranges from 2000°K to 3000°K and excellent agreement obtained with sodium line reversal measurements. Temperatures of pulsed flames have been determined from photographic traces obtained with a monochromator-photo-multiplier-oscilloscope-camera combination. Two high speed light choppers were used, one to interrupt the radiations entering the monochromator and the other to interrupt, at a different frequency, the radiations from a hydrogen discharge lamp transmitted by the flame to the monochromator. The time resolution was 0.10 millisecond and the accuracy in temperature measurement about 40°K in the range 2000°K to 3000°K. The method was calibrated by means of sodium line reversal although it is easily adaptable to absolute calibration.
J. A. CURCIO, H. S. STEWART, and C. C. PETTY, "A Method for the Determination of Flame Temperature from Emission in the Ultraviolet OH Band," J. Opt. Soc. Am. 41, 173-176 (1951)