Measurement of leakage in a novel gas seal at high
temperatureAlain AndersonGraduate Research Assistant
Luis San AndrésMast-Childs Professor
32nd Turbomachinery Research Consortium Meeting
May 2012
TRC 32513/15193S/ME
Trends in High Performance Turbomachinery- More compact units (reduce axial length)- Extreme operating temperatures and pressures- More efficient & reliable
Justification
Issues of Importance- Reduce parasitic leakage- Reduce specific fuel consumption & COST- Increase power delivery- Eliminate potential for rotordynamic instability
Source: Siemens
Two year program (2010-12)- Conduct leakage tests with a HALOTM seal and a
three teeth labyrinth seal at- High temperatures (300°C) and high surface
speeds (120 m/s: 15 krpm)
TRC project objectives
Outcomes- Enable the application of new sealing technology- Increase system efficiency
- Reduce leakage- Eliminate wear of components- Extend maintenance intervals
HT seal test rig
HOT AIR
EXHAUST DUCT
AIR OUT
1 Tapered roller bearings
7 Quill shaft
2 Shaft 8 Flexible coupling
3 Disk 9 Test seal
4 Pressure vessel 10 Metal Mesh Foil Bearing
5 Air inlet 11 Position rods
6 Motor 12 Eddy current sensors (X and Y directions)
Air gas Constant 287 J/kg-K
Supply Pressure, Ps 1.01 – 9.09 bar
Inlet Temperature, Ts 298 K - 573 K
Exhaust Pressure, Pa 1.01 bar
Ambient Temperature, Ta 298 K
Bearing assembly
Hot air inlet100 psig MAX
Shaft
Eddy current sensors
MMFB
Disk
Test seal
Journal
HT seal test rig
Test seals
Labyrinth Seal3 teeth
HALOTM SealCantilever pad
Test seals
Labyrinth SealMaterial 4140 SteelCoefficient of Thermal Expansion 12.3 10-6/°COuter Diameter 183.05 mmInner Diameter (Upstream) 167.28 mmInner Diameter (Downstream) 167.10 mmAxial Length 8.48 mmPad Allowable Radial Movement 0.27 mmPad Axial Length, l 8.05 mmPad Arc Length (40°) 58.42 mmNumber of Pads 9Beam Axial Width 6.40 mmDiametral Clearance 0.43 mm
HALOTM SealMaterial 4140 SteelCoefficient of Thermal Expansion 12.3 10-6/°COuter Diameter 183.11 mmInner Diameter 167.35 mmAxial Length, l 8.40 mmNumber of Teeth 3Teeth Tip Width 0.17 mmCavity Depth 3.0 mmDiametral Clearance 0.49 mm
Disk Material 4140 Steel
Coefficient of Thermal Expansion 12.3 10-6/°C
Outer Diameter 166.85 mm
Disk Thickness 44.45 mm
Hydrostatic Advanced LOw Leakage SealAll metal non-contacting seal
The HALOTM seal
UpstreamFlowPa Ps
LEAKAGE: Labyrinth seal
Flow rate decreases with gas temperature
due to: surfaces thermal
expansionlower air densityhigher viscosity
No rotational speed
LEAKAGE: HALOTM seal
No rotational speed
HaLO’s leakage is a fraction of
labyrinth seal.Seal can
withstand higher pressures.
Leakage Comparison: two seals
Labyrinth seal
HALOTM
seal
HALO seal has ~ 1/5 of the leakage in a labyrinth seal with ~ same clearance
Flow Factor Comparison: two seals
Flow factor removes effect of temperature and seal size.HALO seal is very effective at high pressures because it is a controlled clearance seal.
DPTm
s
Labyrinth seal
HALOTM
seal
No rotational speed
TRC project current status
• Leakage tests with both seals: rotation up to 3 krpm
• Estimations of drag power loss
• Timely modifications for operation at high rotor speed (12 krpm) await a new student
Questions (?)
In progress: