Rotordynamic characteristics of rotating labyrinth gas turbine seal with centrifugal growth

The rotordynamic characteristics of gas turbine seals have been investigated in numerous previous studies. However, the effects of centrifugal growth were often ignored; and no extensive studies have been reported. To this end, the present work examines numerically the influence of centrifugal growth on the rotordynamic characteristics of a typical rotating labyrinth gas turbine seal. A computational framework developed based on combined 3D FE/CFD methodology along with an appropriate rotordynamic model has been employed. For a given seal clearance and eccentricity, various flow and operating conditions are investigated covering a range of pressure ratios and rotational speeds. A substantial variation in both the cross-coupled stiffness and direct damping is noticed and the influence increases with rotational speed. The stability characteristics reveal that centrifugal growth of the seal has a detrimental effect at relatively low pressure ratio and high rotational speed combinations. The computational approach is validated against a typical labyrinth seal results reported in the literature.