Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting

[摘要] Rotors in high-performance steam turbines experience a significantaxial shifting during starting and stopping processes due tothermal expansion, for example. This axial shifting couldsignificantly alter the flow pattern and the flow-inducedrotordynamic forces in labyrinth seals, which in turn, canconsiderably affect the rotor-seal system performance. This paperinvestigates the influence of the rotor axial shifting on leakagerate as well as rotordynamic forces in high-low labyrinth sealsover a range of seal clearances and inlet swirl velocities. Awell-established CFD-perturbation model was employed to predictthe rotordynamic coefficients. A surprisingly large effect wasdetected for rotordynamic characteristics due to rotor shifting.It was also found that a less destabilizing effect arose fromrotor axial shifting in the leakage flow direction, whereas a moredestabilizing effect arose from shifting against the leakage flowdirection. Further, a tentative explanation was proposed for thelarge sensitivities of dynamic forces to rotor axial shifting.

[学科分类] 力学，机械学