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Aerospace Seals - Long-life Turbine Seals
Research Objectives
  • Develop durable, low-leakage turbomachinery seals to meet demands of next generation subsonic and supersonic engines.
  • Develop seal design methods and analytical techniques to assess engine performance impact of advanced seals in a complex secondary air system.
Specific Goals
  • Develop seal technology to reduce specific fuel consumption (SFC) 2%.
  • Validate seal performance and design models through lab. testing under simulated speeds, temperatures, and pressures.
  • Demonstrate seal performance in full scale engine tests.
  • Transition seals to engine service.
Technical Challenges
  • Limited material (seal and coating) strength and durability under extreme temperature and surface speeds.
  • Need for state of the art facilities to subject seals to required extreme conditions.
  • Analysis: Need to model complex, multiple engine cavity and seal flow fields.
Current Research
Current research aims to verify and refine design methodology for non-contacting finger and brush seals for subsonic engine applications using experimental data and analysis. These compliant seals have very small seal-to-rotor clearances, which minimizes seal leakage rates and reduces specific fuel consumption and emissions. Their compliant features allow the seals to accommodate thermal and centrifugal growth and shaft dynamic motion while maintaining a low seal clearance with little to no wear, providing long life capability. NASA's baseline non-contacting finger seal inner diameter has concentric lift pads that ride on a thin film of air over the herringbone grooves on the test rotor. Initial spin tests at 300 K and 5000 rpm produced no measurable wear after 25 minutes. Leakage rates were less than a third of a 4-tooth labyrinth seal and less than half of a contacting brush seal.

Inner diameter of NASA's baseline non-contacting finger seal
Above: Inner diameter of NASA's baseline non-contacting finger seal.
Turbine Seal Timeline
70s: Ludwig, Zuk, DiRusso and others develop hydrodynamic face seals plus design methods for turbine engines.

70's-80's: Bill, Sovey, Handschuh and others investigate blade tip seals; Abradable pads to reduce blade tip wear; Seal Materials to prevent titanium compressor blade fires

Early 90's: Hendricks, Schlumberger, Proctor and others investigate brush seals for turbo machinery: turbine engine and cryogenic turbopumps; Hendricks, Liang, Proctor and others work on family of seal codes: Industrial (design) & Scientific (CFD); Steinetz, Sirocky develop rope seal, ceramic wafer seal and others for 2000°F NASP engine

Mid 90's thru today: Addy, Proctor, Hendricks, Steinetz test SiC Bristle brush seals, finger seals; Steinetz, Adams, Dunlap investigate rope seals for turbine engine and Shuttle booster seals; Proctor, Steinetz, Delgado investigate non-contacting finger seals.
Turbine Seal Timeline
Noncontacting Finger Seal
Proctor, M. P. and Steinetz, B. M.
US Patent No. 6,811,154 Link to non-NASA website Issued: Nov. 2, 2004

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Margaret Proctor
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NASA Seals and Secondary Flows Symposium

November 19, 2013 - Postponed to Nov. 2014 due to Government Shutdown in October. Watch for new date.

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Last Updated: May 5, 2009