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: