Flowmeters for cryogenic applications often fail in service. Turbine flowmeters in particular fail due to very high speeds encountered during chill-down operations. Very cold, very high-velocity gas causes the turbine to spin uncontrollably, which quickly degrades bearings. Those flowmeters that do not fail are often unreliable, degrading their effectiveness as instrumentation to monitor and control cryogenic propellant loading.
This work describes more robust flowmeters that will allow more accurate, safe loading operations, and allow more straightforward chill-down operations, simplifying and shortening the loading process. This innovation improves the reliability and useful life of flowmeters for cryogenic applications.
A magnetic field is used to brake and slow the flowmeter blades when excessively high-velocity gas flow is detected. The magnetic field automatically prevents the turbine from over-speeding until gas velocities subside, providing for less bearing wear, longer flowmeter life, and more reliable measurement. Magnetic field is not intrusive. No extra penetrations to the flow path are required to apply the brake and slow the turbine rotation.