The Experimental Study On Vibration Characteristics Of High-Speed Turbine Rotor With Generator

Mobile distributed energy system which its core power device is high-speed Microturbomachinery (MTM) will be one of the important development directions of clean energy technology in the future, as MTM with application of gas bearing has the advantages of compact structures,high power density,high speed, low power consumption of gas bearings, et al. Gas bearings, however, have low damping, load-carrying capacity and stability in high speed due to the inherently small gas viscosity, so vibration characteristics and stability of the high-speed rotor supported by gas bearings is one of the key technology which gas bearings were applicated to the high-speed rotor machines.Based on high-speed turbine-generator rotor system supported by gas bearing, experimental investigations of the vibration characteristics and influence of supply pressure and foundation damping on the stability of high-speed turbomachinery shaft were carried out, and the main work of the thesis is as follows:1. The expressions of amplitude-frequency and phase-frequency response in the critical speed region were derived base on the Jeffcott model. In the light load conditions, the whirl expression was derived, combined with the motion equation of rotor-bearing system, then the characteristics of whirl and whip were carried out.2. Total of six order critical speed of high-speed turbine-generator rotor system with four disk, single span and two thrust disc supported by gas bearing, with gas film stiffness was calculated in range from 1.0×106N/m to 6.0×106N/m of the direct stiffness of gas film force with the ANSYS software.3. Based on the analysis spectrum of nonlinear vibration behavior such as bifurcation plot,3D plot of frequency coupling, shaft center orbits, frequency spectrum plot, Bode plot, nonlinear methods for test, measurement and analysis were carried out from three aspects of the fundamental frequency vibration, low frequency vibration and rotor rub fault, in order to provide analysis method for vibration characteristics and stability of rotor system and evidences for failure identifying in the following research.4. The bench of high-speed turbine rotor with generator supported by gas bearings was built, which illustrated the whole bench system including gas supply system, body part of test bench, control system and data acquisition and analysis system. The bench aims to achieve control and measure the parameters of bearing gas pressure, store and analyze the data of vibration, monitor the vibration of rotor online and test rig remotely.5. Experimental investigations of the typical vibration characteristics of high-speed turbine rotor supported by gas bearings were carried out. Based on nonlinear methods for test, measurement and analysis such as bifurcation plot, frequency spectrum plot,3D plot of frequency coupling, the experimental results show the typical characteristics of shaft system vibration, such as critical speed, half-speed whirl, gas whip, double low frequency whirl, speed-soaring process and rub fault. It aims to provide some experimental evidences for identification of typical nonlinear dynamical characteristics of gas bearing-rotor system.6. Experimental investigations of the effect of supply pressure and foundation damping on the stability of high-speed turbomachinery shaft were carried out. The results show that 1) the critical speed and the speed of subsynchronous whirl (i.e. half-speed whirl, gas whip, double low frequency whirl) increases with the supply pressure increasing and as the damping of the system reduces with the supply pressure increasing,the critical vibration amplitude and the amplitude of half-speed whirl and gas whip increase.2)The external damping of shaft system increases effectively as the foundation of bench with silicone damping pad, then the vibration amplitude of critical speed and gas whip reduces, thus improve the stability margin of rotor system.