Measurement of leakage in a novel gas seal at high temperature - - PowerPoint PPT Presentation

Measurement of leakage in a novel gas seal at high temperature

Alain Anderson

Graduate Research Assistant

Luis San Andrés

Mast-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 inlet 100 psig MAX Shaft Eddy current sensors MMFB Disk Test seal Journal

HT seal test rig

Test seals

Labyrinth Seal

3 teeth

HALOTM Seal

Cantilever pad

Test seals

Labyrinth Seal

Material 4140 Steel Coefficient of Thermal Expansion 12.3 10-6/°C

Outer Diameter 183.05 mm

Inner Diameter (Upstream) 167.28 mm Inner Diameter (Downstream) 167.10 mm Axial Length 8.48 mm Pad Allowable Radial Movement 0.27 mm Pad Axial Length, l 8.05 mm Pad Arc Length (40°) 58.42 mm Number of Pads 9 Beam Axial Width 6.40 mm

Diametral Clearance 0.43 mm

HALOTM Seal

Material 4140 Steel Coefficient of Thermal Expansion 12.3 10-6/°C Outer Diameter 183.11 mm Inner Diameter 167.35 mm Axial Length, l 8.40 mm Number of Teeth 3 Teeth Tip Width 0.17 mm Cavity Depth 3.0 mm Diametral 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 Seal

All metal non-contacting seal

The HALOTM seal

Upstream Flow

Pa Ps

LEAKAGE: Labyrinth seal

Flow rate decreases with gas temperature due to:

• surfaces thermal

expansion

• lower air density
• higher 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.

D P T m

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: