HIGH-RESOLUTION FORCE MEASUREMENT SYSTEMS: MEASURING HORIZONTAL DIRECTED FORCES FOR FLOW METERING OF LOW CONDUCTIVE MEDIA IN CHANNELS

摘要

Recent advance in flow metering of electrolytes through contactless method of Lorentz Force Velocimetry (LFV) demands application specific developments of high precision horizontal force measurement systems. In contrast to the measurand Lorentz force- directed horizontally and ranges as 10~(-8)-10~(-5) N -there is 10N vertically acting dead load accompanying measurements. In this work we present overview of two force measuring setups resolving these measurements particularly suitable for metering flow velocity of purely conducting liquids in channels. The first setup is based on principle of differential force measurements and uses two equivalent state-of-the-art electromagnetic force compensation (EMC) precision weighing balances in order to compensate mechanical vibrations and force drift. Measurement resolution of 20-30 nN in the range of up to 100μN is achived. The second, optimized, setup demonstrates applicability of measurement method for the same horizontal forces based on direct EMC principle. The term 'direct' in last indicating the fact that in the setup EMC is done using magnetic field of high power magnet system. Magnets are required component of LFV setup and are suspended from force measuring setup producing 10N unavoidable dead load.