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Cooperation with Deutsche WindGuard – an operator of large wind tunnel facilities


In many fields of industry – such as for example air-conditioning, environmental technology, meteorology, aviation or wind energy – information about flow velocity is of substantial importance. Measurement devices for detecting the measurand flow velocity, for example vane anemometers, are usually calibrated in wind tunnels.
PTB operates two wind tunnels for the realization and dissemination of the unit flow velocity. The larger of the two with a cross-sectional area of 0.1 m² is of medium size and suited for calibrations in a velocity range of less than 1 m/s up to over 60 m/s.

For the calibration of anemometers, interactions between the test item and the flow field in the wind tunnel have to be considered. These interactions are dependent on the dimension, the construction and the functional principle of the anemometer as well as on the size of the wind tunnel. Different calibration methods and correction factors are, thus, applied. Therefore, it is not astonishing that international comparison measurements do not necessarily show a comparability of calibration results within the documented measurement uncertainties. Only large wind tunnels with large cross-sectional nozzle areas and large measuring field lengths, compared to the dimensions of the anemometers, allow the realization of almost interaction independent flow conditions and, thus, ideal reference conditions for the assessment of anemometer calibrations.

Based on a cooperation agreement between Deutsche WindGuard GmbH and PTB, PTB now has access to larger wind tunnels. The Deutsche WindGuard company is a developer, operator and owner for four wind tunnels covering nozzle sized with cross-sectional areas from 1 m² for calibration wind tunnels up to 11 m². These facilities will be used for joint research and development work. Equipped with PTB reference and transfer standards, they can serve as reference wind tunnels
Deutsche WindGuard has experience of over 20 years in anemometer calibration, performs its own research activities and is involved in international committees.
Of special interest is the new wind tunnel Varel 2, which is identically constructed to the 1 m² calibration wind tunnel accredited up to now but extended in its velocity range from below 1 m/s up to over 35 m/s delivering small turbulence intensities and high spatial coherence. Within the future cooperation, this wind tunnel will allow us to perform calibrations with uncertainties of U < 0.5 %.

At present Deutsche WindGuard is an accredited testing laboratory for wind turbines as well as an accredited calibration laboratory for anemometers and it provides international services in the wind energy sector. Deutsche WindGuard Wind Tunnel Services GmbH, a subsidiary of Deutsche WindGuard GmbH, implements more than 50 % of the worldwide anemometer calibrations in the field of wind energy, is a member of MEASNET, and international measurement network of facilities in the field of wind energy and a member of the Wind Energy Agency Bremerhaven/Bremen with more than 200 companies and institutions.
Tus, the cooperation between PTB and Deutsche WindGuard provides the best preconditions to realize reference conditions for the calibration of different kinds of anemometers and to ensure the comparability of the calibration results.

Contact person:

Helmut Többen, Dept. 1.4, E-Mail: helmut.toebben@ptb.de