Hot-wire anemometry and cylinder-wake analysis

Paper · Project 65

This paper covers experimental aerodynamic measurement with hot-wire anemometry: full sensor characterization, calibration, and analysis of a circular cylinder wake.

Sensor characterisation

The probe's dynamic response was determined through impulse analysis, obtaining a cutoff frequency of 10 kHz and confirming suitability for resolving the turbulent fluctuations of interest.

Calibration used King's Law over a velocity range of 3–20 m/s:

E² = A + B · Uⁿ with A = 2.336, B = 2.127, n = 0.4628

achieving a fit accuracy of R² = 0.9998, which enables reliable conversion of voltage signals into instantaneous velocity.

King's Law calibration fit/assets/img/papers/hotwire-kings-law.png

Fig. 1 — Final King's law calibration curve.

Wake analysis

The wake of a circular cylinder of D = 32 mm was analysed using high-frequency sampling, computing power spectral densities to identify vortex shedding frequencies and their dependence on freestream velocity.

Power spectral densities at three freestream velocities/assets/img/papers/hotwire-psd-results.png

Fig. 2 — Power spectral density for 4, 8 and 12 m/s.

Results

Turbulence statistics revealed significant velocity deficits and high turbulence intensity of 27–32% in the wake. Time-frequency analysis via STFT tracked the shedding frequency evolution, confirming temporal stability and agreement with Strouhal-based theoretical predictions.

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