A cooled-gas pyrometer for use in high-temperature gas streams

Lloyd N. Krause, Robert C. Johnson, George E. Glawe
naca-tn-4383
Sep 1958


An immersion-type pyrometer is described that utilizes the controlled cooling of a continuously aspirated sample of the gas whose temperature is to be measured. The gas is cooled as it is drawn through a tube, after which its temperature is measured with a thermocouple. Free-stream total temperature is then obtained by a relation involving internal heat transfer in the tube, gas properties, and certain readily measured temperatures and pressures. A technique is described whereby calibration constants obtained in air at near room total temperature are used to compute the high-temperature correlations for other gases with known property values. Experimental comparison in a high-temperature gas stream with thermocouple probes and with a pneumatic-probe pyrometer showed agreement within 2 percent of total temperature in the range 2000 to 4000 degrees R.

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