Methods are presented for parameter identification of an annular gas seal on a flexiblerotor
test rig. Dynamic loads are applied by magnetic bearings (MBs) that support the
rotor. MB forces are measured using fiber-optic strain gauges that are bonded to the
poles of the MBs. In addition to force and position measurements, a finite element (FE)
rotor model is required for the identification algorithms. The FE rotor model matches
free-free characteristics of the test rotor. The addition of smooth air seals to the system
introduces stiffness and damping terms for identification that are representative of
reaction forces in turbomachines. Tests are performed to experimentally determine seal
stiffness and damping coefficients for different running speeds and preswirl conditions.
Stiffness and damping coefficients are determined using a frequency domain
identification method. This method uses an iterative approach to minimize error
between theoretical and experimental transfer functions. Several time domain
approaches are also considered; however, these approaches do not produce valid
identification results. Stiffness coefficients are measured using static test results and an
MB current and position based model. Test results produce seal coefficients with low
uncertainties for the frequency domain identification method. Static test uncertainties
are an order of magnitude larger, and time domain attempts fail to produce sealIn addition to the primary identification research, an investigation of the relationships
between MB force, strain, and magnetic field is conducted. The magnetic field of an
MB is modeled using commercial FE software. The magnetic field model is used to
predict strain measurements for quasi-static test conditions. The strain predictions are
compared with experimental strain measurements. Strain predictions agree with
experimental measurements, although strain is typically over-predicted.
coefficient measurements.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1827 |
| Date | 02 June 2009 |
| Creators | Zutavern, Zachary Scott |
| Contributors | Childs, Dara |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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