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Research Papers: Gas Turbines: Structures and Dynamics

Experimental Investigation of a Leaf Seal Prototype at Engine-Representative Speeds and Pressures

[+] Author and Article Information
Michael J. Pekris

Structures & Transmissions,
Rolls-Royce plc.,
Derby DE24 8BJ, UK
e-mail: michael.pekris@rolls-royce.com

Gervas Franceschini

Structures & Transmissions,
Rolls-Royce plc.,
Derby DE24 8BJ, UK
e-mail: gervas.franceschini@rolls-royce.com

Ingo H. J. Jahn

School of Mechanical and Mining Engineering,
University of Queensland,
Brisbane, QLD 4072, Australia
e-mail: i.jahn@uq.edu.au

David R. H. Gillespie

Department of Engineering Science,
University of Oxford,
Oxford OX1 3PJ, UK
e-mail: david.gillespie@eng.ox.ac.uk

1Corresponding author.

Contributed by the Structures and Dynamics Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received September 14, 2015; final manuscript received October 1, 2015; published online December 4, 2015. Editor: David Wisler.

J. Eng. Gas Turbines Power 138(7), 072502 (Dec 04, 2015) (9 pages) Paper No: GTP-15-1449; doi: 10.1115/1.4031875 History: Received September 14, 2015; Revised October 01, 2015

The application of compliant filament seals to jet engine secondary air systems has been shown to yield significant improvements in specific fuel consumption and improved emissions. One such technology, the leaf seal, provides comparable leakage performance to the brush seal but offers higher axial rigidity, significantly reduced radial stiffness, and improved compliance with the rotor. Investigations were carried out on the Engine Seal Test Facility at the University of Oxford into the behavior of a leaf seal prototype at high running speeds. The effects of pressure, speed, and cover plate geometry on leakage and torque are quantified. Earlier publications on leaf seals showed that air-riding at the contact interface might be achieved. Results are presented which appear to confirm that air-riding is taking place. Consideration is given to a possible mechanism for torque reduction at high rotational speeds.

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References

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Figures

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Fig. 1

Leaf seal schematic

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Fig. 2

Schematic diagram of the Oxford Engine Seal Test Facility

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Fig. 3

Test procedure: leaf seal run-down test on the Engine Seal Test Facility

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Fig. 4

Effective clearance versus seal upstream pressure, 6000 rpm speed, all seal configurations

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Fig. 5

Effective clearance versus seal upstream pressure, 2000 rpm speed, all seal configurations

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Fig. 6

Two-seal torque versus rotor speed, seal upstream pressure LBD: UCP(0.25–3) and DCP(0.25–2)

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Fig. 7

Two-seal torque versus rotor speed, seal upstream pressure SBD: UCP(0.35–3) and DCP(0.15–3)

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Fig. 8

Two-seal torque versus rotor speed, seal upstream pressure LLU: UCP(0.25–2) and DCP(0.25–3)

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Fig. 9

One-dimensional flow in a tapered channel

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Fig. 10

Incompressible channel flow local Reynolds number

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Fig. 11

Incompressible and compressible flow pressure distributions for 0.2 MPa upstream pressure

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Fig. 12

Incompressible and compressible flow pressure distributions for 0.4 MPa upstream pressure

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Fig. 13

Incompressible and compressible flow tip forces for various tapered channel geometries for 0.2 MPa upstream pressure

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Fig. 14

Incompressible and compressible flow tip forces for various tapered channel geometries for 0.4 MPa upstream pressure

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Fig. 15

Taper height for various speeds at each seal location (thin and thick rotor sections)

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Fig. 16

Lift force per leaf for various speeds at each seal location (thin and thick rotor sections) for 0.2 MPa and 0.4 MPa upstream pressures

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