Thermocouple shape influence on response in a dynamic compressible fluid atmosphere

This investigation was performed to determine whether the geometrical shape of a thermocouple used to measure the temperature of a dynamic fluid atmosphere had any affect on its recovery factor and time response. A converging nozzle was used to establish a dynamic fluid stream in which shaped silver solder junctions of copper-constantan thermocouples were tested. The velocity of the working fluid, air, was about 1000 ft/sec at the test point. The investigation was successful, within experimental limits, in determining that the recovery factor of a bare thermocouple junction is not influenced by geometrical shape The results agreed substantially with available results of other investigators and empirical equations used to predict this parameter. The findings for time response, indicate that geometrical shape influences time response. The number of tests ran was insufficient and equipment errors coupled with procedural problems preclude that the degree of variation could be determined with quantitive certainty. The procedure and equipment used, if evaluated by comparing the results obtained with that of accepted sources, was satisfactory. The test setup could be used to obtain good results by modifying it to reduce or account for the more serious errors encountered --Abstract, page 2