This dissertation discusses research on the leakage and rotordynamic characteristics
of pocket damper seals (PDS) and see-through labyrinth seals, presents and evaluates
models for labyrinth seal and PDS leakage and PDS force coefficients, and compares
these seals to other annular gas seals. Low-pressure experimental results are used
alongside previously-published high-pressure labyrinth and PDS data to evaluate the
models. Effects of major seal design parameters; blade thickness, blade spacing, blade
profile, and cavity depth; on seal leakage, as well as the effect of operating a seal in an
off-center position, are examined through a series of non-rotating tests. Two
reconfigurable seal designs were used, which enabled testing labyrinth seals and PDS
with two to six blades.
Leakage and pressure measurements were made with air as the working fluid on
twenty-two seal configurations. Increasing seal blade thickness reduced leakage by the
largest amount. Blade profile results were more equivocal, indicating that both profile
and thickness affected leakage, but that the influence of one factor partially negated the
influence of the other. Seal leakage increased with increased eccentricity at lower
supply pressures, but that this effect was attenuated for higher pressure drops. While
cavity depth effects were minor, reducing depths reduced leakage up to a point beyond
which leakage increased, indicating that an optimum cavity depth existed. Changing
blade spacing produced results almost as significant as those for blade thickness,
showing that reducing spacing can detrimentally affect leakage to the point of negating the benefit of inserting additional blades. Tests to determine the effect of PDS partition
walls showed that they reduce axial leakage. The pressure drop was found to be highest
across the first blade of a seal for low pressure drops, but the pressure drop distribution
became parabolic for high pressure drops with the largest drop across the last blade.
Thirteen leakage equations made up of a base equations, a flow factor, and a kinetic
energy carryover factor were examined. The importance of the carryover coefficient
was made evident and a modified carryover coefficient is suggested. Existing fullypartitioned
PDS models were expanded to accommodate seals of various geometries.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85848 |
| Date | 10 October 2008 |
| Creators | Gamal Eldin, Ahmed Mohamed |
| Contributors | Vance, John M. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, born digital |
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