Michael George Hvasta, Daniel Dudt, Adam E. Fisher, and Egemen Kolemen

"Calibrationless rotating Lorentz-force flowmeters for low flow rate applications"

Measurement Science and Technology, 2018

http://iopscience.iop.org/article/10.1088/1361-6501/aac3b5

Abstract:  A 'weighted magnetic bearing' has been developed to improve the performance of 
rotating Lorentz-force flowmeters (RLFFs).  Experiments have shown that the new bearing 
reduces frictional losses within a double-sided, disc-style RLFF to negligible levels.  
Operating such an RLFF under 'frictionless' conditions provides two major benefits.  
First, the steady-state velocity of the RLFF magnets matches the average velocity of the 
flowing liquid at low flow rates.  This enables an RLFF to make accurate volumetric flow 
measurements without any calibration or prior knowledge of the fluid properties.  Second, 
due to minimized frictional losses, an RLFF is able to measure low flow rates that cannot 
be detected when conventional, high-friction bearings are used.  This paper provides a 
brief background on RLFFs, gives a detailed description of weighted magnetic bearings, 
and compares experimental RLFF data to measurements taken with a commercially available 
flowmeter.