Lorentz force anemometry
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Lorentz force anemometry (abbreviated LKA) is a non-contact electromagnetic flow measurement method for electrically conductive fluids . The Lorentz force - anemometer is particularly suitable for flow measurements in liquid metals and is therefore currently on their applicability in aluminum - and steel industry explored. A Lorentz force anemometry system is also known as a Lorentz force anemometer.
principle
The basic principle of Lorentz force anemometry is shown in the figure. If an electrically conductive fluid such as liquid aluminum moves in a pipe under the influence of a magnetic field generated by a permanent magnet , eddy currents are generated in the fluid . These induce an electromagnetic force, the Lorentz force, which counteracts the movement of the fluid. According to Newton's third law "force = counterforce" ( actio = reactio ), an equally strong but oppositely directed force acts on the permanent magnet. This force is proportional to the mean speed as well as to the electrical conductivity of the fluid. By measuring this force, it is possible to determine the flow velocity of the fluid.
Liquid metals and electrolytes are para- or diamagnetic and are therefore only attracted or repelled to an extremely small extent by a permanent magnet. The creation of the Lorentz force used in the LKA has nothing to do with classical magnetic attraction or repulsion forces. It is exclusively due to eddy currents , the strength of which depends on the electrical conductivity, the speed of movement and the amplitude of the magnetic field.
history
Lorentz force anemometry was invented by the English physicist Arthur Shercliff in the 1950s. However, it found no practical use for several decades. It was only with the development of high-performance permanent magnet systems, precise force measurement methods and special simulation software that it became possible to bring this technology to industrial maturity. Lorentz force anemometers are currently being developed for applications in metallurgy and are on the threshold of being ready for the market.
literature
- Arthur J. Shercliff: Theory of Electromagnetic Flow Measurement . Cambridge University Press, ISBN 978-0-521-33554-6 .
- A. Thess, EV Votyakov, Y. Kolesnikov: Lorentz Force Velocimetry . In: Physical Review Letters . tape 96 , no. 16 , 2006, pp. 164501 , doi : 10.1103 / PhysRevLett.96.164501 . (free download - open access)
- Y. Kolesnikov, C. Karcher, A. Thess: Lorentz Force Flowmeter for Liquid Aluminum: Laboratory Experiments and Plant Tests . In: metal. Mat. Trans. B . 42B, 2011, p. 241-250 ., Doi : 10.1007 / s11663-011-9477-6 . (free download - open access)
- A. Thess, E. Votyakov, B. Knaepen, O. Zikanov: Theory of the Lorentz Force Flowmeter . In: New Journal of Physics . tape 9 , 2007, p. 290. , Doi : 10.1088 / 1367-2630 / 9/8/299 . (free download - open access)
- J. Priede, D. Buchenau., G. Gerbeth: Single-Magnet Rotary Flowmeter for Liquid Metals . In: J. Appl. Phys. tape 110 , 2010, p. 03451. , Doi : 10.1063 / 1.3610440 .
- X.-D. Wang, Yu. Kolesnikov, A.Thess: Numerical Calibration of a Lorentz Force Flowmeter . In: J. Meas. Sci. Tech. tape 23 , 2012, p. 045005. , Doi : 10.1088 / 0957-0233 / 23/4/045005 . (free download - open access)
Web links
- TU Ilmenau: Research Training Group LORENTZ FORCE (homepage of the DFG graduate college "Electromagnetic flow measurement and eddy current testing using Lorentz force")
Individual evidence
- ↑ Statement from Y. Kolesnikov, C. Karcher, A. Thess: Lorentz Force Flowmeter for Liquid Aluminum: Laboratory Experiments and Plant Tests . In: metal. Mat. Trans. B . 42B, 2011, p. 241-250 ., Doi : 10.1007 / s11663-011-9477-6 .