Analysis and Experimental Test of a 200 kW Oil-Free Micro Gas Turbine Simulator

This paper presents the measured rotordynamic performance and model predictions of a 200 kW oil-free micro gas turbine simulator (MGTS). The MGTS has a single spool configuration, and a gas generator rotor (GTR) and an electric motor rotor (EMR) connected by a diaphragm coupling and supported on gas foil journal bearings (GFJBs). A couple of double acting gas foil thrust bearings (GFTB) are used inside the gas turbine. The MGTS is a full-size replica of a 200 kW micro gas turbine, with the exception of the impeller blades of the compressor and turbine. The design of the diaphragm coupling determines the first and second bending critical speeds of the MGTS. A speed-up test was conducted up to 40 krpm to evaluate the rotordynamic stability of the rotor-bearing system. The test results showed that the synchronous motion had several peaks, which were due to the rigid modes of the rotor-bearing system. The highest peak occurred at ~10 krpm and was produced by the second bending mode of the coupling. The results for 40 krpm revealed the occurrence of small amplitude synchronous motions. The predicted critical speeds of the rotor-bearing system and synchronous rotor motions were in good agreement with test data.