Journal of Theoretical
and Applied Mechanics

54, 1, pp. 305-310, Warsaw 2016
DOI: 10.15632/jtam-pl.54.1.305

Binormal cooling errors in single hot-wire measurements

Ramis Örlü, P. Henrik Alfredsson
In single-wire hot-wire measurements, velocity fluctuations acting normal to the hot-wire and its prongs will cause additional heat transfer known as binormal cooling. With respect to wall turbulence, the influence of this additional cooling is well-studied for crossed wires, while it is commonly ignored in single hot-wire measurements. The latter view is challenged
in the recent work by Dróżdż and Elsner (2014) that claims significant errors in variance measurements when using single-wire probes in turbulent boundary layers. This short communication revisits these claims and quantifies binormal cooling errors through an expansion of the effective-velocity concept and utilisation of direct numerical simulation data. Results
support the common habit that binormal cooling errors can safely be ignored in single hot-wire measurements.
Keywords: hot-wire anemometry, measurement errors, wall turbulence