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Report on the First-Generation NIST Convective Heat Flux Calibration Facility.


pdf icon Report on the First-Generation NIST Convective Heat Flux Calibration Facility. (1689 K)
Holmberg, D. G.; Womeldorf, C. A.

NIST SP 971; NISTIR 6197; 17 p. August 2001.

NIST SP 971: "Collected Reports and Publications by the National Institute of Standards and Technology on Heat Flux Gage Calibration and Usage.", 2001.

Available from:

For More Information on NIST SP 971 visit: WEBSITE: http://www.bfrl.nist.gov/866/heatflux/index.htm
Order number: PB99-150071

Keywords:

heat flux; calibration; convection; standards; uncertainty

Abstract:

The National Institute of Standards and Technology has developed a convective heat flux calibration facility to allow evaluation of heat flux sensors. This facility is a small wind tunnel that produces a two-dimensional laminar boundary layer across a heated iso-thermal copper plate. This facility has been developed to allow convection calibration of heat flux sensors to complement heat flux sensor calibrations presently conducted using standard radiation methods, recognizing that many sensors are used in mixed radiation and convection environments. By extending calibration capabilities to include a primarily convective environment, direct comparisons of sensors in controlled convective and radiative environments are possible. This report describes the first-generation heated plate design, analysis, and performance. The reference heat flux on the plate is found from the electrical power input to a guarded region of the plate to the side of the sensor in spanwise uniform flow. Tests have demonstrated a repeatability on the reference heat flux of + 1.5%. A detailed uncertainty analysis of the reference heat flux value is presented showing lateral conduction to surrounding regions of the plate to be the greatest source of uncertainty with plate surface emissivity the only other significant source. The calculated relative expanded uncertainty (95% level of confidence) on the measured reference heat flux value is + 4.6%. The average reference heat flux from these tests agrees with numerical predictions within 2%.