Determination of the Uncertainty of Experimental Heat-Flux Calibrations

摘要

A description and the results of a study of the uncertainty associated with experimental calibration of heat-flux transducers/gages performed at the Arnold Engineering Development Center (AEDC) are given. Determination of an overall or total calibration uncertainty was achieved by combining the results of different groups of experimental calibrations performed at the AEDC and the National Bureau of Standards (NBS), respectively. The first group of calibration data was obtained by calibrating six heat-flux transducers fabricated in-house at the AEDC versus calibration standard slug calorimeters also fabricated at the AEDC. The radiant heat source used in the calibrations was a nine-unit (1-kw max/unit) quartz tube lamp bank. A classical precision term was calculated for each of the six transducers from the results of these experimental calibrations. Acquisition of the second group of calibration data was achieved by sending the same six transducers to the Fire Research Center of the NBS in Washington, D.C. for experimental calibration services. Thus, traceability to NBS heat-flux standards was achieved. A radiant heat source was also used by the NBS and the calibrations were performed in a manner similar to the procedures employed at the AEDC. Calibration data obtained at the AEDC and the NBS were compared to determine a bias value for each of the six transducers. A total uncertainty value for each transducer was calculated by combining the precision and bias terms. The average total uncertainty calculated for the six transducers was nominally plus or minus percent. (Author)