1. TRC project
TRC 32513/15193S/ME
Measurement of leakage in a novel all metal non-contacting annular seal at high temperature
Alain Anderson
Graduate Research Assistant
Luis San Andrés
Mast-Childs Professor
START DATE: September 1, 2010

2. JUSTIFICATION Issues of Importance
Trends in High Performance Turbomachinery
Higher speeds & more compact units
Extreme operating temperatures and pressures
More efficient & reliable
Issues of Importance
Reduce secondary flows
(parasitic leakage)
Reduce specific fuel consumption & COST
Increase power delivery
Eliminate potential for rotordynamic instability
Source: GE Energy

3. OBJECTIVE TRC funded a two-year program
Conduct non-proprietary leakage tests with a HALOTM seal
Conduct leakage tests with a three tooth labyrinth seal for comparison
Desired outcomes
Enable the application of state of the art sealing technology
Increase system efficiency
Reducing leakage
Eliminating wear of components
Extending maintenance intervals

4. PRIOR WORK [1]
A power gas turbine OEM wished to benchmark novel seal types against a (traditional) labyrinth seal to realize benefits and to ensure potential gains
To measure leakage in three test seals by varying:
Supply pressure (upstream) from 1 bar to 3.5 bar
Air inlet temperature from 30ºC to 300ºC
Rotor speed from 0 rpm to 3,000 rpm
To estimate drag torque (power loss) from each seal
Compare three seals and provide recommendations

5. TEST SEALS [1]
Labyrinth Seal Brush Seal
Hybrid Brush Seal

6. EXPERIMENTAL FACILITY

7. EXPERIMENTAL FACILITY
Test seal 8 3 2 5 4 6 1 7
Flow in (supply pressure)
Flow out (ambient pressure) 10 20 cm

8. EXPERIMENTAL FACILITY
Centering mechanism
Test seal
Maximum air pressure: 100 psig

9. Proposal to TRC (2 years)
TRC members benefit from existing high temperature seal test rig
a) Revamp test rig for operation at higher rotor speeds to reach a tip surface speed of 120 m/s (15 krpm). Thermal and centrifugal growth at high speeds is expected to further decrease leakage
b) Perform clearance and leakage measurements with a three teeth labyrinth seal and the HALOTM seal operating with pressure ratios as high as 8, temperatures to 300ºC, and tip surface speeds to 120 m/s
c) Compare the labyrinth seal measured leakage with XLLaby® predictions at high temperature. The benchmarking is essential to trust, modify or discard current predictive models 9

10. TRC funded project (2 years)
TRC members benefit from existing high temperature test rig
a) Revamp test rig for operation at higher rotor speeds to reach a tip surface speed of 120 m/s (15 krpm). Thermal and centrifugal growth at high speeds is expected to further decrease leakage
b) Perform clearance and leakage measurements with a three teeth labyrinth seal and the HALOTM seal operating with pressure ratios as high as 8, temperatures to 300ºC, and tip surface speeds to 120 m/s
c) Compare the labyrinth seal measured leakage with XLLaby® predictions at high temperature. The benchmarking is essential to trust, modify or discard current predictive models 10

11. Non-rotating and centered rotor
Work to date for TRC funded project
Learn operation of test rig and DAQ system
Install two seals (labyrinth and HALO) and perform leakage measurements with air for:
Revamp test rig for high speed operation
Inlet temperature (30ºC-300ºC)
Supply pressure (1 bar- 7 bar)
Non-rotating and centered rotor

12. TEST LABYRINTH SEAL 12

13. LEAKAGE: Labyrinth Seal
30C
300C
Flow rate increases with supply pressure and decreases with inlet temperature due to changes in seal clearance and gas density.
TESTS for low pressure ratios to 3.5 (> choking)

14. Modified flow factor: Labyrinth Seal
Flow factor allows comparison of different types of seals. For labyrinth seal, it removes effect of supply pressure and temperature.

15. TEST HALOTM Seal Hydrostatic Advanced Low Leakage Seal
All metal (no bristles) non-contacting seal 20 10 mm
Direction of flow

16. TEST CONDITIONS (HALOTM SEAL)

17. PR: upstream pressure /ambient (exit) pressure
Hydrostatic Advance Low Leakage (HALO) Seal
HALO™ seal clearance closes with pressurization.
Measurements at room temperature (30 °C) and no shaft rotation
PR: upstream pressure /ambient (exit) pressure

18. LEAKAGE: HALOTM Seal
30C
300C
Flow rate increases with supply pressure and decreases with air inlet temperature. TESTS conducted with much higher pressure ratios

19. Modified flow factor: HALOTM Seal
Modified flow factor much lower than for labyrinth seal

20. Leakage Comparison: Labyrinth & HALO)
HALO seal
The HALOTM seal leaks 50% or less than the labyrinth seal. For pressure ratios (Ps/Pa) > 3.0, the HALOseal leaks ~¼ the flow rate of the labyrinth seal

21. Flow factor (Labyrinth & HALO) 300 C
HALO seal
Labyrinth seals are an outdated technology. Industries seeking to increase efficiency by reducing (parasitic) secondary leakage losses will benefit greatly from a change in seal technology 21

22. REVAMP TEST RIG Issues Solutions
For operation at higher rotor speeds to reach a tip surface speed of 120 m/s (15 krpm)
Issues
Solutions
Balance rotor
For high temperature, use a metal mesh foil bearing (MMFB) as a support.
Use high speed router motor & construct containment guard.
Large vibrations of cantilevered rotor
Critical speeds too low & air temperature too high
Safety: containment at high speeds
Drive motor speed limitations

23. REVAMP TEST RIG XLTRC2 rotordynamic analysis
Metal mesh bearing support adds stiffness and damping to original cantilevered rotor.

24. XLTRC2 imbalance response predictions
Amplitude of motion at disc
With MMFB
MMFB increases critical speed and determines a well damped system 24

25. High Temperature Seals
TRC Budget
High Temperature Seals
Year II
Support for graduate student (20 h/week) x $ 1,700 x 12 months
$ 20,400
Fringe benefits (0.6%) and medical insurance ($191/month)
$ 2,412
Travel to (US) technical conference
$ 1,500
Tuition three semesters ($3,802 x 3)
$ 10,138
Equipment and supplies for test rig $
$ 35,000
Year I
$ 39,863
Research will quantify the leakage performance of a novel gas seal for high temperature gas turbines and steam turbines.
RESEARCH PRODUCTS
Reliable leakage database
ASME journal publication
Technical report (M.S. thesis) 25

26. Questions (?)

27. References Learn more at http://rotorlab.tamu.edu
[1] San Andrés, L., and Ashton, Z., 2010, "Comparison of Leakage Performance in Three Types of Gas Annular Seals Operating at a High Temperature (300°C)," Tribol. Trans., 53(3), pp
[2] Justak, J., and Doux, C., 2009, “Self-Acting Clearance Control for Turbine Blade Outer Air Seals,” ASME Paper GT
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