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The determination of fluctuating velocity in air with heated thin film gauges

Published online by Cambridge University Press:  28 March 2006

B. J. Bellhouse
Affiliation:
Department of Engineering Science, University of Oxford
D. L. Schultz
Affiliation:
Department of Engineering Science, University of Oxford

Abstract

When attempts are made to use thin film anemometers in airflow to measure fluctuating velocity it is found that the dynamic sensitivity cannot be obtained from a steady-flow calibration. It is found that the dynamic sensitivity is considerably less than that predicted by static calibration and that the sensitivity is frequency-dependent. It is shown that thermal feedback from the substrate, on which the gauge is mounted, to the heated element is responsible for the variation of sensitivity with frequency, despite constant-temperature operation of the probe, and this variation is examined theoretically and experimentally.

Type
Research Article
Copyright
© 1967 Cambridge University Press

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References

Bankoff, S. G. & Rosler, R. S. 1962 Constant-temperature hot-film anemometer as a tool in liquid turbulence measurements Rev. Sci. Instrum. 33, 120912.Google Scholar
Bellhouse, B. J. & Schultz, D. L. 1966 Determination of mean and dynamic skin friction, separation and transition in low-speed flow with a thin-film heated element J. Fluid Mech. 24, 379400.Google Scholar
Curle, N. 1962 The Laminar Boundary Layer Equations. Oxford Mathematical Monographs.