Noise reduction of UDV measurements in liquid metal experiments with high magnetic fields


Noise reduction of UDV measurements in liquid metal experiments with high magnetic fields

Seilmayer, M.; Stefani, F.; Gundrum, T.

The last decades have seen a number of liquid metal experiments on the interaction of magnetic fields and the flow of electrically conducting fluids. The opaqueness of liquid metals requires non-optical methods for inferring the velocity structure of the flow. Quite often, such experiments are carried out with very high electrical currents to generate the necessary magnetic fields. Depending on the specific purpose, these currents can reach several kA. The utilized switching mode power supply can then influence seriously the UDV measurements by electromagnetic interference. As an example, a recent experiment on the azimuthal magnetorotational instability (AMRI) has shown that a hydrodynamically stable Taylor-Couette flow becomes unstable under the influence of a high azimuthal magnetic field. An electrical current on the axis of the experiment with up to 20 kA generates the necessary field to destabilize the flow. We will present experimental results on this AMRI experiment carried out at the PROMISE facility with an enhanced power supply. For this system, we discuss the elaborate measures that were needed to obtain a reasonable signal-to-noise ratio of the ultrasonic measurement system. In dependence on various parameter variations, some typical features of the observed instability, such as the energy content, the wavelength, and the frequency are analyzed and compared with theoretical predictions.

Keywords: Taylor-Couette flow; magnetic fields; noise reduction; UDV

  • Contribution to proceedings
    9th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering, 27.-29.08.2014, Strasbourg, France
    Proceedings of the 9th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering

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Publ.-Id: 20309