Method for calibrating a heat flux gauge
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsAlan H. Epstein, Gerald R. Guenette, Robert J. G. Norton
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Abstract
Double-sided, high-frequency response heat flux gauge for use on metal tune blading consists of a metal film (1500A) resistance thermometer sputtered on both sides of a thin (25 .mu.m) polyimide sheet. The temperature difference across the polyimide is a direct measure of the heat flux at low frequencies, while a quasi-one-dimensional analysis is used to infer the high-frequency heat flux from the upper surface history. A new method of calibrating the heat flux gauge utilizes light source applied to a plurality of fluids covering the surface of the gauge, measuring the temporal output of the gauge and utilizing derived calibration formula.
Claims21
A method for providing heat flux gauge measurements for use in calibrating said heat flux gauge comprising the steps of:
- insuring that the surface of said, heat flux gauge has an emissivity greater than 0.1 over the wavelength band of a light source to be used in calibration;
- covering the surface of said heat flux gauge with a first fluid of known thermal properties;
- applying a light source of known modulation to an area encompassing said heat flux gauge;
- measuring a temporal electrical output of a sensor of said gauge;
- covering the surface of said heat flux gauge with a second fluid that replaces said first fluid, said second fluid being of known thermal properties;
- applying said light source to an area encompassing said heat flux gauge;
- and
- measuring the temporal electrical output of said sensor of said gauge.
A method for calibrating a heat flux gauge comprising the steps of:
- insuring that the surface of the heat flux gauge has an emissivity greater than 0.1 over the wavelength band of a light source to be used in the calibration;
- covering the surface of said sensor with a first fluid of known thermal properties;
- applying a light source of known modulation to an area encompassing said gauge;
- measuring a temporal electrical output of a sensor of said gauge;
- covering the surface of said heat flux gauge with a second fluid that replaces said first fluid, said second fluid being of known thermal properties;
- applying said light source to an area encompassing said heat-flux gauge;
- measuring the temporal electrical output of said sensor of said gauge;
- and
- applying the calibration formula ##EQU36## wherein M.sub.I and M.sub.II are the the slopes of the linear region of sensor electrical output vs time when immersed in the respective first and second fluids, s referring to the second fluid, F referring to the first fluid, .rho.=density, k=thermal conductivity and c=specific heat.
A method for calibrating a heat flux gauge comprising the steps of:
- insuring that the surface of the heat flux gauge has an emissivity greater than 0.1 over the wavelength band of a light source to be used in the calibration;
- covering the surface of said sensor with a first fluid of known thermal properties;
- applying a light source of known modulation to an area encompassing said gauge;
- measuring a temporal electrical output of a sensor of said gauge;
- covering the surface of said heat flux gauge with a second fluid that replaces said first fluid, said second fluid being of known thermal properties;
- applying said light source to an area encompassing said heat flux gauge;
- measuring the temporal electrical output of said sensor of said gauge;
- and
- applying the calibration formula ##EQU37## wherein M.sub.I and M.sub.II are the slopes of the linear region of sensor electrical output vs. time when immersed in the respective first and second fluids, F referring to the first fluid, .rho.=density, k=thermal conductivity of gauge substrate, c=specific heat, d=distance across gauge substrate and (T.sub.u -T.sub.l).sub.ss =steady-state temperature difference between the upper and lower surfaces of the gauge.
Dependencies are inferred from the claim text.