Rotordynamic forces developed by labyrinth seals.
Numerous developments have been completed towards the accurate measurement and prediction of the fluid/structure interaction forces on labyrinth seals. The test facility was refined and data acquisition automated. Measurements were obtained of both stiffness and damping force coefficients for two labyrinth seal configurations operating with small rotor motion about its centred position. Only the cross coupled damping coefficient exhibits significant sensitivity to shaft speed and the coefficients increase monotonically with increasing supply to discharge pressure ratio. Fluid prerotation exhibits a strong influence on cross coupled stiffness which increases and decreases, respectively, with prerotation in and opposite to the direction of shaft rotation. Direct damping is less sensitive to fluid prerotation and, is generally larges for prerotation against the shaft direction. A simple Iwatsubo based force coefficient model was also developed. Predictions obtained from the approximate model are much more sensitive to shaft speed than corresponding current measurements and damping values are approximately one quarter of those measured. (A)
author list (cited authors)
Childs, D. W., & Rhode, D. L.