Regensburg 2007 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 5: Fluid dynamics I

DY 5.2: Talk

Monday, March 26, 2007, 14:30–14:45, H2

Development of a sphere-anemometer for measuring wind velocities in the open air test site — •Bianca Schulte, Michael Hölling, Stephan Barth, and Joachim Peinke — Institut für Physik, Universität Oldenburg

In nature wind rarely occurs in a laminar form, but the wind flow is mostly turbulent. Therefore, it is necessary to use a setup with short response time to measure the current wind velocity. On the other hand the setup has to withstand the harsh conditions of an open air test site. The conventional cup-anemometer often used in an open air situation has the drawback that the response time at increasing and decreasing wind velocity is different. This asymmetric inertia of the anemometer leads to a wrong averaging of the current wind velocity. Conversely the fast responding hot wire anemometer can not be utilized in long term free field measurements because of its aging and vulnerability of the filigree wire.

A new kind of anemometer, the sphere-anemometer, is presented to overcome these problems. This kind of anemometer principle relies on drag acting on a sphere which is fixed to the end of a flexible rod. The deflection of the rod gives a measure for the force acting on the sphere and is measured by means of a light pointer. In wind tunnel measurements we compared the three devices in a wake configuration. The signals taken from the different setups are opposed via statistical methods.