200kW Oil-free Micro Gas Turbine Simulator Analysis and Experiment
- 200kW Oil-free Micro Gas Turbine Simulator Analysis and Experiment
- 구본진; 김창호; 이종성; 김태호; 심규호
- micro gas turbine; foil bearing; rotordynamics; high temperature bearing; oil-free
- Issue Date
- IFToMM International Conference on Rotordynamics
- This paper presents the rotordynamic performance measurements and model predictions of 200kW oil-free micro gas turbine simulator(MGTS). The MGTS is a single spool configuration with gas generator turbine rotor(GTR) and electric motor rotor(EMR) connected by diaphragm coupling and supported on gas foil journal bearings(GFJBs). A total of five GFJBs supports the two rotors, and a couple of double acting gas foil thrust bearings(GFTB) are located inside the gas generator turbine. This MGTS copies the 200kW micro gas turbine at its actual size except impeller blades of compressor and turbine. The GTR with its length of 501 mm, diameter of 85 mm, and weight of 286 N is supported on three GFJBs, and the EMR with its length of 549 mm, diameter of 86 mm, and weight of 183 N is supported on two GFJBs. The turbine end of GTR is in ~600°C, and two GFJBs support the GTR in 300~400°C. The predicted thermal expansion of the GTR changes the bearing clearance with its radius ~100μm. Stiffness of bump foils of the GFJB is estimated from measured bump structural stiffness, and compared with prediction from computational model. The main design goal of GFTBs is high load capacity, and the load capacity is optimized in inclined angle, outer diameter and bump foil design. The diaphragm coupling transmits rotating force from one rotor to another and isolates radial dynamic force. Coupling shaft is thick enough to be considered as rigid, so the thickness of diaphragm controls the stiffness of the diaphragm coupling. Design of the diaphragm coupling determines 1st and 2nd bending critical speeds of MGTS. Speed-up test is conducted up to 40 krpm to evaluate rotordynamic stability of the rotor-bearing system. The acceleration of the rotating speed is ~2500 rpm/s for suppressing radial vibration of the rotor at the critical speeds. A set of orthogonally positioned displacement sensors measure horizontal and vertical motions of the GTR at...
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