Experimentelle Untersuchungen zur Anwendbarkeit der Lorentzkraft-Anemometrie auf schwach leitfähige Fluide
In times of sustainable energy savings and steadily rising commodity prices, life withoutflow measurements is unthinkable. Be it metering of waste water, or gauging at a gas station,everybody insists on paying only for what they consumed. Despite the variety ofexisting flow meters, some applications remain where the volume flux can be measuredonly with high uncertainty if at all. The measurement is particularly difficult if the flow tobe measured is opaque, extremely hot, and chemically aggressive.Lorentz force velocimetry (LKA or LFV) represents a solution to these problems. This noncontactflow measurement method has been patented at Ilmenau University of Technologyin 2005 and relies on the electromagnetic interaction between an electrically conductingfluid and an externally imposed magnetic field. Metallurgical applications of LFV areparticularly promising due to the high electrical conductivities involved. Currently, firstprototypes are being tested under industrial conditions.This thesis is concerned with the question whether LFV can be extended to the measurementof weakly conductive fluids. In contrast to metallurgy, Lorentz forces in the orderof F < 1E-5 N must be resolved. In this thesis, two LFV prototypes have been built whichhave been especially adapted for the measurement of salt water flows. With these prototypesthe suitability of LFV for the flow measurement of weakly conducting fluids hasbeen demonstrated experimentally for the first time. The work confirms the theoreticallypredicted linear dependence between the Lorentz force and the flow rate as well as theelectrical conductivity of the weakly conductive fluid (Thess et al.). Moreover, this thesisshows how different magnetic fields and velocity fields affect the measured Lorentz force.