Rotordynamic Forces Developed by Labyrinth Seals
Annual rept. 1 Sep 1983-31 Aug 1984
AIR FORCE OFFICE OF SCIENTIFIC RESEARCHBOLLING AFB DC
Pagination or Media Count:
Numerous developments have been completed toward the accurate measurement and prediction of the fluid-structure-interaction forces on labyrinth seals. The test facility was refined and data acquisition was automated. Measurements were obtained of both stiffness and damping force coefficients for two labyrinth seal configurations operating with small rotor motion about its centered 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 pre- rotation exhibits a strong influence on cross-coupled stiffness, which increases and decreases, respectively, with pre-rotation in and opposite to the direction of shaft rotation. Direct damping is less sensitive to fluid pre-rotation, and is generally largest for pre-rotation against the shaft direction. A simple Iwatsubo-based force coefficient model was also developed. Predictions obtain from the approximate model are much more sensitive to shaft speed than corresponding current measurements, and damping values are approximately one- fourth of those measured.
- Adhesives, Seals and Binders
- Fluid Mechanics