The calibration of (multi-) hot-wire probes. 1. Temperature calibration

A. van Dijk, F.T.M. Nieuwstadt

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13 Citations (Scopus)

Abstract

We study the performance of the classical relation for the correction for ambient temperature drift of the signal of a hot-wire anemometer and the influence of practical assumptions. It is shown that most methods to estimate the operational temperature via the temperature/resistance coefficient lead to underestimation of the operational temperature and thus to overcorrection of signals for temperature drift. We found that, in the presence of a sensible heat flow, temperature fluctuations cannot be sufficiently removed from the hot-wire signal when one relies on temperature/resistance coefficients from literature. When only slow temperature drift is involved, most literature values give a satisfactory temperature correction, but this depends on the specific combination of a probe and a literature reference. Therefore it is generally advisable to calibrate the value. A method that uses a ratio of (measured) resistances as a function of temperature, which does not require estimation of the operational temperature of the wire, is shown to depend crucially on a parasitic resistance of a few tenths of an ohm. This parameter can be found by optimizing its value using data from a collection of velocity calibrations at different temperatures. This additional calibration alone suffices to estimate the operational temperature of the wire via optimization. A quick calibration procedure (15 min) is proposed and tested.
Original languageEnglish
Pages (from-to)540-549
JournalExperiments in fluids
Volume36
Issue number4
DOIs
Publication statusPublished - 2004

Keywords

  • velocity-gradients
  • fluid temperature
  • flow

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