Özet:

Most of the major faults in gas turbines often originate from the rotor shaft. Some of these faults could result to misalignment, imbalance, crack, rub-impact and eccentricity. This study analyzes nonlinear factors such as lube-film surge and thermal-stress. Seal and bearing quality significantly affect the performance of a rotor system. The nonlinear dynamic characteristics of a high-temperature rotor–bearing–seal coupled system are investigated. Dynamic trajectories, Poincaré maps, frequency spectra diagrams are used to analyze the features of the rotor-bearing-seal coupled system in terms of various parameters. Several nonlinear phenomena in the high-temperature rotor–bearing–seal coupled system, such as periodic, double-periodic, multi-periodic, and quasi-periodic motion are investigated. Through these curves and the program, the dynamic characteristics of gas turbine rotors could be easily and accurately calculated. To validate this method, the critical speed of a real rotor of an actual gas turbine was calculated by means of the program and curves. The results are consistent with the measured data and may contribute to further understanding the nonlinear dynamics of the high-temperature rotor-bearing-seal coupled system.

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