Measurement of High Temperatures in High-Velocity Gas Streams

Abstract

Abstract Conventional methods of measuring temperatures are subject to considerable errors, when applied to gas streams at velocities around 500 fps and temperatures of the order of 1600 F, which conditions occur, for example, in the exhaust-gas pipe of an airplane engine. An investigation of this problem the results of which are reported in this paper was suggested by the Special Subcommittee on Exhaust Gas Turbines and Intercoolers of the N.A.C.A. and was carried out with the assistance of the Subcommittee on Exhaust Gas Temperature Measurement of the Committee on Industrial Instruments and Regulators. Tests were conducted on the thermocouple, which at present is the most satisfactory temperature-measuring device available, to develop a shield and mounting that would achieve maximum accuracy and minimum size and weight for airplane application. The results indicate that something better than the ordinary thermocouple mountings is required for even a fair degree of accuracy with either the high velocities or temperatures considered. A few tentative devices are suggested which will serve until further studies have been made and more adequate solutions provided.