Nonlinear Dynamic Study on Effects of Flywheel Eccentricity in a Turbine Generator with a Squeeze Film Damper

This study presents the nonlinear dynamics of a turbine generator subjected to an unbalance force caused by mass eccentricity of the flywheel. The proposed turbine generator is equipped with a squeeze film damper under the effect of rub-impact in the oil film rupture. This system consists of a turbine rotor, generator, flywheel with mass eccentricity, and a squeezed film damper. The turbine and generator are connected by a coupling which is regarded as rigid. System equations of motion are formulated by the Global Assumed Mode Method (GAMM) and the Lagrange's approach. This study investigates the nonlinear behavior of the system, including the trajectory of the rotor in the time domain, frequency spectrum, Poincare map, and bifurcation diagram, by solving the system's equation of motion with the Runge-Kutta method. Results show that the system displays period-one motion when the rotor speed ratio is very small under the effects of flywheel eccentricity. However, the periodic motion is suddenly transformed into aperiodic motion without any transition. The squeeze film damper fails to support the rotor if the speed ratio is in the interval between 0.93 and 1.065 when flywheel eccentricity is 1e-4m. And the interval of speed ratio shifted to between 0.5 and 1.06 and when flywheel eccentricity increases to 5e-4 m.