Insertion Depth Effect for Vane Anemometers

J. Geršl, J. Sluše

Abstract

In this paper we show that velocity indication of a vane anemometer in a wind tunnel can significantly and non-trivially depend on length of the part of the anemometer’s mounting rod which is exposed to flow – the so-called insertion depth. The insertion depth dependencies for four vane anemometers with various dimensions are presented. For a small size vane anemometer with a propeller diameter of 22 mm, for example, a change of the insertion depth by 10 cm can cause a reading variation by up to 5 % - a value which is an order of magnitude larger than a typical expanded uncertainty of calibration in wind speed laboratories of national metrology institutes. Therefore, this effect has important consequences for selection of transfer standards for interlaboratory comparisons, since each participant can have a different insertion depth value, and also for the calibration practice where possible differences between the insertion depth of the user and the calibration laboratory should be taken into account.

Keywords

Insertion depth; Vane anemometers; Wind tunnel calibrations

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IMEKO-TC9-2019-052.pdf

DOI

10.21014/tc9-2022.052

IMEKO TC

TC9 - Flow Measurement

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