INTEGRATION OF MAGNETIC BEARINGS IN THE DESIGN OF ADVANCED GAS-TURBINE ENGINES

Active magnetic bearings provide revolutionary advantages for gas turb ine engine rotor support. These advantages include tremendously improv ed vibration and stability characteristics, reduced power loss, improv ed reliability, fault tolerance, and greatly extended bearing service life. The marriage of these advantages with innovative structural netw ork design and advanced materials utilization will permit major increa ses in thrust-to-weight performance and structural efficiency for futu re gas turbine engines. However, obtaining the maximum payoff requires two key ingredients. The first is the use of modern magnetic bearing technologies such as innovative digital control techniques, high-densi ty power electronics, high-density magnetic actuators, fault-tolerant system architecture, and electronic (sensorless) position estimation. This paper describes these technologies and the test hardware currentl y in place for verifying the performance of advanced magnetic actuator s, power electronics, and digital controls. The second key ingredient is to go beyond the simple replacement of rolling element bearings wit h magnetic bearings by incorporating magnetic bearings as an integral part of the overall engine design. This is analogous to the proper app roach to designing with composites, whereby the designer tailors the g eometry and load-carrying function of the structural system or compone nt for the composite instead of simply substituting composites in a de sign originally intended for metal material. This paper describes meth odologies for the design integration of magnetic bearings in gas turbi ne engines.