World-unique Permanent Maglev Turbine Reaches a Speed Over 30,000 rpm

The author's former works on developing a permanent maglev heart pump have been questioned because the rotor of the heart pump has only ca. 20g weight and there is liquid in the pump. To levitate a heavier rotor with passive magnetic(PM) bearing and to avoid the possibility that a fluid bearing may act on the levitation of the rotor, the author applied the passive magnetic bearing in turbine machine. A prototype of permanent maglev gas turbine was developed. The device has a rotor and a stator, both radial and axial PM bearings were used to support the rotor weighing over 2kg. The gap between the rotor and the stator was 1mm, thereby no possible air bearing can be built up to support the rotor together with the PM bearings. First experiment by a model permanent maglev turbine demonstrated that the rotor's maximal eccentric distance, measured by 4 Hall sensors, would be smaller than the gap between the rotor and the stator, if the rotating speed was higher than 1800rpm, indicating that the rotor had no contact with the stator and thus was levitated stably under the action of PM bearing alone. In more extensive experiments with this prototype, the rotating speed of the device reached 30,773rpm, a value approaching that in practical application. It can be concluded that PM bearing can merely support the rotor of a gas turbine being suspended fully and stably in the stator, same as that in blood pump; this result may overturn the principle acknowledged worldwide for hundreds years that permanent maglev could not be stable.