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Design and Uncertainty Analysis of a Second-Generation Convective Heat Flux Calibration Facility.

pdf icon Design and Uncertainty Analysis of a Second-Generation Convective Heat Flux Calibration Facility. (642 K)
Holmberg, D. G.; Womeldorf, C. A.; Grosshandler, W. L.

NIST SP 971; August 2001.

NIST SP 971: "Collected Reports and Publications by the National Institute of Standards and Technology on Heat Flux Gage Calibration and Usage." AND Calibration, Error Analysis, and Modeling of Heat Flux Sensors Symposium. Proceedings. American Society of Mechanical Engineers (ASME) Heat Transfer Division. Volume 4. HTD-Vol. 364-4. November 14-19, 1999, Nashville, TN, American Society of Mechanical Engineers, New York, NY, 65-70 pp, 2001.

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calibrating; convection; heat flux; standards; uncertainty


The National Institute of Standards and Technology has developed a convective heat flux facility to allow calibration of heat flux sensors. The facility consists of a small wind tunnel that produces a two-dimensional laminar boundary layer across a heated isothermal copper plate. Sensors are mounted flush in the copper plate alongside a reference to measure the heat leaving the plate. Convective calibrations up to 5 kW/m2 are possible. Sensor output is compared with the reference value, and contrasted with a standard radiation calibration. Recognizing that many sensors are used in mixed radiation and convection environments, this facility provides a unique opportunity to assess a sensor's convective response. This report describes a second-generation heated plate and provides an analysis of the system uncertainty. Redundant references, improved sensor heating and mounting, improved reference isolation, and a minimized radiation component has reduced the combined relative expanded uncertainty of the reference to +2.5%. The benefits of an embedded temperature sensor in the heat flux sensor are describedThe facility is available for comparative calibrations and for heat transfer studies by individual researchers.