Helmholtz-Zentrum Dresden-Rossendorf E.v.

Technische Universitaet Dresden

Forschungszentrum Dresden-Rossendorf E.v.

Commissariat a L'energie Atomique Et Aux Energies Alternatives

Technische Universitát Dresden

Sven Eckert

Gunter Gerbeth

Thomas Gundrum

Frank Stefani

Petr A Nikrityuk

Dirk Raebiger

Bernd Willers

Kerstin Eckert

Roger Grundmann

Manfred Ziemann

Hans-Walter Katz

Uwe Hewelt

Gunther Gerbeth

Domenique Buchenau

Nico Krauter

Dirk Räbiger

The invention relates to a method and to a device for the electromagnetic stirring of electrically conductive fluids in the liquid state and/or in the state of onsetting solidification of the fluid, using a rotating magnetic field that is produced in the horizontal plane of a Lorentz force. The aim is to achieve an intensive three-dimensional flow on the inside of the fluid for mixing in the liquid state up to the direct vicinity of solidifying fronts, and to simultaneously ensure an undisturbed, free surface of the fluid. The solution is to change the direction of rotation of the magnetic field rotating in the horizontal plane at regular time intervals in the form of a period duration, wherein the frequency of the directional change of movement of the magnetic field vector is adjusted such that in the state of mixing the liquid fluid a period duration is adjusted between two directional changes of the magnetic field during a time interval as a function of the adjustment time with the condition (I) 0.5&#xb7;t&#x3c;T&#x3c;1.5&#xb7;tand such that, at the beginning of the state of onsetting solidification of the fluid, a period duration is set between two directional changes of the magnetic field in a time interval as a function of the adjustment time with the condition (II) 0.8&#xb7;t&#x3c;T&#x3c;4&#xb7;t, wherein the adjustment time; is specified by the equation (III) in which after an activation of the rotating magnetic field in a fluid in the resting state the double vortex of the meridional secondary flow forms, and in which &#x3c3; is defined as the electric conductivity, &#x3c1; as the density of the fluid, &#x3c9; as the frequency, Bas the amplitude of the magnetic field, and Cas the constant for the influence of the size and shape of the volume of the fluid.

Method and device for the electromagnetic stirring of electrically conductive fluids

The invention relates to an ultrasonic sensor for measuring flow rates in liquid melts at high temperatures. The aim of the invention is to provide an ultrasonic sensor for carrying out local, continuous, reliable rate measurements in hot melts. To achieve this, the ultrasonic sensor contains an ultrasonic waveguide that is connected to the piezoelectric transducer and consists of a material with low acoustic damping properties in a temperature range relevant for the area of application of above 200 DEG C, said material being chemically resistant to the melt. In addition, the end face of the ultrasonic waveguide facing the melt is closed and can be wetted by the melt.

Ultrasonic sensor for measuring flow rates in liquid melts

The invention relates to a method for measuring flow rates in liquid melts in a temperature range above 200 DEG C. using an ultrasonic generator and to an associated ultrasonic waveguide according to the ultrasonic Doppler method. The aim of the invention is to provide good signal incoupling and outcoupling. This is achieved by the preparation of the wettability of the end face of the ultrasonic waveguide before the measuring operation, subsequent direct incoupling of ultrasonic measuring signals into the melt at an angle that is not equal to 90 DEG, achieved by the immersion of the end face of the ultrasonic waveguide into the melt, outcoupling of the ultrasonic signals reflected in the melt via the end face of the ultrasonic waveguide and routing of said signals to an evaluation circuit. To prepare the wettability of the end face, the latter is mechanically and chemically cleaned and subsequently coated with a suitable material.

Method for measuring flow rates in liquid melts

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Dresden, Germany

Sven Eckert