The already finished EUROMET project 388 “intercomparison of anemometers” with windmill-type anemometers of different size in laboratories with very different instrumentation for the calibration has shown that there are relatively big differences. The conclusion was that more investigation (mainly concerning the blocking effect) is necessary.
The aim of the proposed project is to accomplish appropriate pre-conditions for a detailed analysis of future calibration results in order to decrease the deviations between calibration laboratories and to reduce the calibration uncertainties for different types of anemometers. The common use of Laser Doppler Velocimeter (LDV) systems as velocity standards in the different calibration facilities ensures ideal conditions to realize low uncertainties for the representation of the flow velocity over a wide velocity range in each facility.
To estimate deviations between the participating calibration laboratories and to find out a common basis, in a first step anemometers with minimal blockage effects (Pitot tube for higher velocities and hot wire anemometer for lower velocities) are calibrated in each calibration laboratory.
Preliminary intercomparison results of the first step performed in the different calibration facilities with different procedures already show a good agreement and provide a good basis for further steps including the calibration of other types of anemometers and enlarging the velocity ranges.