An Accurate Rotor‐Levitated Turbine Flow Meter for Cryogenic Service

Accurate flowrate measurements of cryogenic fluids are difficult and often critical, especially when working with liquid helium or liquid hydrogen. Turbine flowmeters, extensively used at room temperature, show a good repeatability, provided that friction between rotor and stator remains low and constant. Traditional bearings used to sustain the rotor are subjected to wear and tear which can change the friction value, resulting in a change of the calibration factor with hardly noticeable evidence to the user. Working in cryogenic conditions makes it possible to adopt passive non‐contact bearings by taking advantage of the properties of superconductors.At the Istituto di Metrologia Colonnetti (IMGC), a prototype of low‐temperature turbine flowmeter with the rotor magnetically levitated was developed; the rotor levitates thanks to the interaction between rare‐earth magnets and melt‐textured YBCO superconductors. Such configuration ensures a high value of the forces acting on the rotor which, however, needs ...