Squeeze Film Damper Technology. Part 3. Experimental Investigation of Squeeze Film Dampers

摘要

A test rig was constructed and proper instrumentation provided for measuring the performance of squeeze film dampers. The tests provided both conceptual understanding of the mechanism of damper operation by providing data on the viscous and inertia components of the fluid film, and on the modalities of oil delivery via the feeding holes and grooves, for both sealed and unsealed dampers. Quantitative data were then provided for the entire gamut of variables attending the design of squeeze film dampers and these were then compared with theoretical predictions. A particularly important part of the test was the visual documentation via both still and motion pictures of cavitation which is still not a fully understood phenomenon under dynamic conditions. Failure tests were conducted to simulate damper response to extreme loadings such as resulting form loss of a turbine blade. While the correlation with theory was shown to be generally valid up to the upper ranges of speeds, the quality of correlation was much affected by the encountered variation of boundary conditions in the feed grooves. The latter thus emerges as an aspect of squeeze film damper mechanics which needs further study.