Local flow structures in liquid metals measured by ultrasonic Doppler velocimetry

Ultrasound Doppler velocimetry (UDV) has been successfully applied to measure local velocities in mercury and the eutectic alloy InGaSn. Two different kinds of magnetic fields established the fluid motion in a cylindrical vessel. For both, the rotating and the traveling field, agreement with expectations from theory and local measurements employing different techniques was achieved.
The deliverance of a profile by UDV instead of one value at one fixed co-ordinate, typical for almost any other method, allowed for the determination of the topology in a plane covered by the ultrasonic beam while the sensor was traversed. These area-wide results are, by nature, time averaged respectively mean velocities.
The range of flow regimes regarding the magnitude of velocity which is detectable by means of the Doppler procedure begins already in the turbulent region. For the case of the rotating magnetic field spectral distributions of time series of velocity signals measured at different positions in the fluid volume will be presented.