Three flexure pivot pad bearings (FPBs) with different preloads are evaluated for
use in high performance applications by comparing them to a hybrid hydrostatic bearing
(HHB). One application of these bearings is in turbopumps for liquid rocket engines.
To evaluate bearing performance, the lift-off speed of the shaft from the bearing surface
is experimentally determined. Experimental data of lift-off are collected using a circuit
running through the shaft and the designed bearing. Other methods for measuring liftoff
speeds were attempted but did not yield consistent results. Water is used as a
lubricant to simulate a low viscosity medium.
In comparison to load-capacity-based predictions for FPBs, the experimental
results showed lower lift-off speeds, higher load capacities, higher eccentricity ratios,
and lower attitude angles. The bearings’ predicted load capacity determined lift-off
speed predictions, but the experimental results show no clear trend relating lift-off speed
to load capacity. This was for a range of running speeds, with the design speed defined
as the final speed in a particular test case.
At 0.689 bar supply pressure and for a design speed of 3000 rpm, the HHB
showed greater load capacities and lower eccentricities than the FPBs, but the FPBs had
lower lift-off speeds and attitude angles. In fact, the FPBs in the load-between-pad
orientation outperformed the HHB in the load-on-pocket orientation with lower lift-off
speeds for the shaft weight-only case. An increased supply pressure lowered the lift-off
speeds in the HHB tests. If the load in the bearing application remains relatively small, a
FPB could be substituted for an HHB.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-3197 |
| Date | 15 May 2009 |
| Creators | Mertz, David Hunter |
| Contributors | Childs, Dara |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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