This report deals with the analysis, design and construction of an instrument intended to measure gas temperature in excess of 2000°C. Preliminary experimental calibration of this instrument is compared with those two particular aspects of theoretical behaviour which have been dealt with. A platinum/platinum-rhodium thermocouple was used in calibration to a temperature of 1300°C. The instrument is a conductive-convective heat flux device. A fine stainless steel tube is heated by the hot gas and cooled internally by flowing watero The water is supplied by and returnffi respectively, through one of two copper tubes inside a water cooled stainless steel jacket. It is shown that with proper calibration and analysis the heat flux to the instrument is uniquely defined in terms of only two variables, the tube side pressure drop and the electrical resistance of the needle tubeo The latter quantity can be made constant, however, and the heat flux is related solely to the instrument coolant flow pressure drop. The instrument can be calibrated versus other thermometrie deviees so that the outside film transfer coefficient and temperature can be deduced separately. A linear relationship and a high degree of sensitivity between instrument coolant pressure drop and the external gas temperature was discovered.

Rigorous analyses of tube side pressure drop of a one-dimensional fluid stream in cross-flow heat transfer and the electrical resistance of a thick walled annular conductor with three dimensional cross-flow temperature distribution are performed. Graphs of these quantities versus temperature are plotted for various conditions of heat transfer.