Accession Number : AD0292255

Title :   AN ASSESSMENT OF THE ERRORS INVOLVED IN THICK-FILM HEAT TRANSFER MEASUREMENTS

Corporate Author : BOEING CO SEATTLE WASH

Personal Author(s) : ROSS,PETER A.

Report Date : 05 DEC 1962

Pagination or Media Count : 1

Abstract : A study of the calibration procedure for the thick-film gage constant (P.Cl/(R alpha sub o)) was made to establish calibration acuracy. It was found that the (R alpha) sub o determination by the water-bath method was uncertain within !8% due to Joule heating effects. Analysis of the Joule heating effects led to improvements in the measurement technique, which reduced the (R alpha) sub o error to !0.5%. The error associated with the manufacturer's values of PAND C at a reference temperature of 0 C was found to be !1%. For gage temperatures above 0 C no recommended values are given. Another large uncertainty is in the measurement of l which is fixed at !10% with current measurement techniques. This error, in fact, is the predominant contribution to over-all calibration error at the reference gage temperature (0 C) which is !10%. It was found that relative heat transfer measurements under uniform flow conditions in the shock tube can be obtained within an accuracy of !4%. Thus, for gage temperature variation in the vicinity of 0 C, the absolute heat transfer measuring accuracy by virtue of the !10% calibration error, is about !11%. (Author)

Descriptors :   *CALORIMETERS, *HEAT TRANSFER, *MEASURING INSTRUMENTS, *SHOCK TUBES, CALIBRATION, ERRORS, FILMS, HEAT RESISTANT GLASS, LABORATORY EQUIPMENT, MATHEMATICAL ANALYSIS, PLATINUM

Distribution Statement : APPROVED FOR PUBLIC RELEASE