An Experimental Investigation of the Effect of an Active Magnetic Damper on Reducing Subsynchronous Vibrations in Rotating Machinery

Abstract

Presented here are results from an experimental study investigating the reduction of subsynchronous vibrations in rotating machinery by adding a single active magnetic bearing actuator to a flexible rotor-bearing system. In this scenario, the Active Magnetic Bearing (AMB) actuator is used as an Active Magnetic Damper (AMD) and is not utilized for rotor support. The AMD can be used to increase stability margins by adding more damping in strategic locations on a rotor allowing for increased tolerance to instability mechanisms and enabling increased performance and efficiency in turbomachinery. Results from an experimental 3-mass test rig supported in fluid-film bushings are presented here. The study shows that subsynchronous vibrations are reducible with an AMD located near the mid-span of the rotor and up to a 98% reduction in the amplitude of subsynchronous vibrations is demonstrated. The overall results from this work demonstrate that reduction in subsynchronous response is feasible and that full rotor dynamic analysis and design is critical for the successful application of this approach as critical speed locations can be altered.

Improving stability and operation of turbine rotors using adjustable journal bearings

“…The limitations of JBs stand on the instability mechanism, known as oil whirl and oil whip [25][26] while AMBs cannot support high loads without occupying much space in the machine. The use of AMBs on controlling the JB instability has been also investigated further in [13,[27][28].…”