Dynamic Characteristics of Rotor Seals Influenced by Offset for Ultra-supercritical Steam Turbines
During the operation of ultra-supercritical steam turbines,the unbalanced steam flow impact force can cause steam flow excitation.Taking the labyrinth seal of a 1000MW steam turbine ultra-high pressure cylinder as an example,the improved whirl equation and mesh deformation were used to realize the multi-frequency whirl of the rotor.The effects of different offset on the seal dynamic characteristics were analyzed.The results show that the direct stiffness kyy increases with the increasing of whirl frequency.The direct damping cyy first decreases significantly before 30Hz and then does not change with frequency.As the pressure ratio increases,the effective damping increases,and the stability of the rotor increases.The direct stiffness of the seal kyy increases in the positive direction at each offset.The direct damping cyy decreases greatly with the increasing of frequency and remains approximately unchanged at last.The variation in seal aerodynamic characteristics caused by the offset is strong in the high-pressure region.
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