Experimental Investigations on the Properties and Dynamic Behaviour of a Hybrid Bearing System for Turbo Machines

Within the frame of an international research program that was supported by the European Commission, one subtask was to determine the dynamic behaviour of rotating shafts of turbo machines using a Hybrid Magnetic Bearing Concept (HMBC). This HMBC denotes the combination of Active Magnetic Bearings (AMB) with an additional Permanent Magnetic Bearing (PMB). For the present investigations a permanent magnetic radial shear force bearing was used. Due to their characteristics the conventional active magnetic suspension and the permanent magnetic support affect each other. This mutual action has to be considered at the benefit analysis of a hybrid bearing system. This contribution outlines the scientific approach of these studies. The overarching objective was to make the results sustainable to use. Therefore validated models will be necessary that are able to recreate the dynamic behaviour of a magnetic suspended rotor with the support of an additional permanent magnetic bearing. The basis of this approach is the application of methods of theoretical and experimental modelling. The validation of the created models was made with reference to experimental tests on the FLP 500 test facility in Zittau, Germany. For the necessary experiments the completely AMB-supported test rig was equipped with an additional permanent magnetic radial bearing.