| dc.description.abstract | Squeeze film dampers (SFDs) with low levels of external pressurization and poor
end sealing are prone to air entrapment, thus reducing the damping capability.
Furthermore, existing predictive models are too restrictive. Single frequency,
unidirectional load and centered circular orbit experiments were conducted on a
revamped SFD test rig. The damper journal is 1" in length and 5" in diameter, with
nominal clearance of 5 mils (0.127 mm). The SFD feed end is flooded with oil, while
the discharge end contains a recirculation groove and four orifice discharge ports to
prevent air ingestion. The discharge end is fully sealed with a wave-spring that pushes a
seal ring into contact with the SFD journal. The measurements conducted without and
with lubricant in the squeeze film lands, along with a frequency domain identification
procedure, render the mechanical seal dry-friction force and viscous damping force
coefficients as functions of frequency and motion amplitude. The end seal arrangement
is quite effective in eliminating side leakage and preventing air entrainment into the film
lands. Importantly enough, the dry friction force, arising from the contact forces in
relative motion, increases significantly the test element equivalent viscous damping
coefficients. The identified system damping coefficients are thus frequency and
amplitude of motion dependent, albeit decreasing rapidly as the motion parameters
increase. Identified force coefficients, damping and added mass, for the squeeze film
damper alone agree very well with predictions based on the full film, short length SFD
model. | en |
