The response of hot wires in high Reynolds-number turbulent pipe flow

J. D. Li, B. J. McKeon, W. Jiang, J. F. Morrison, A. J. Smits

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Issues concerning the accuracy of hot-wire measurements in turbulent pipe flow are addressed for pipe Reynolds numbers up to 6 × 106 and hot-wire Reynolds numbers up to Rew ≈ 250. These include the optimization of spatial and temporal resolution and the associated feature of signal-to-noise ratio. Very high wire Reynolds numbers enable the use of wires with reduced length-to-diameter ratios compared to those typical of atmospheric conditions owing to increased wire Nusselt numbers. Simulation of the steady-state heat balance for the wire and the unetched portion of wire are used to assess static end-conduction effects: they are used to calculate wire Biot numbers, √c0l, and fractional end-conduction losses, σ, which confirm the 'conduction-only' theory described by Corrsin. They show that, at Rew ≈ 250, the wire length-to-diameter ratio can be reduced to about 50, while keeping √c0l > 3 and σ < 7% in common with accepted limits at Rew ≈ 3. It is shown that these limits depend additionally on the choice of wire material and the length of unetched wire. The dynamic effects of end-cooling are also assessed using the conduction-only theory.

Original languageEnglish (US)
Pages (from-to)789-798
Number of pages10
JournalMeasurement Science and Technology
Issue number5
StatePublished - May 2004

All Science Journal Classification (ASJC) codes

  • Instrumentation
  • Engineering (miscellaneous)
  • Applied Mathematics


  • Fluid flow velocity
  • Thermal anemometry
  • Turbulence diagnostics


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