Follow this link to go to the text only version of
NASA - National Aeronautics and Space Administration
+ Contact NASA
Structures and Materials Division Research and Technology Directorate NASA Glenn Research Center

Tribology and mechanical Components Branch
Tribology and mechanical Components Home
Research Areas
Computer Codes
Partner with Us
Contact Information
Aerospace Seals - Adaptive Seals
Research Objectives
Develop and demonstrate clearance management technologies to improve turbine engine performance, reduce emissions, and increase service life.
Technical Challenges
  • Clearances between shroud and blade tips vary over the operation and life of an engine. Wear and thermal erosion increases blade tip clearance.
  • Gas path temperatures are >2500 °F, Cooling air temperatures are >1200 °F, Case temperature 600 °F with soak back.
  • Actuators must react ~2000 lbf, move ~0.050 inch in 10 seconds.
  • Current clearance control systems accurate to 0.015- 0.020 inch. Accuracy of <0.005 inch is goal.
  • Small, lightweight active clearance control systems required. Weight < 100 lbs is goal.

Current Research
NASA Glenn Research Center is developing a unique Active Clearance Control (ACC) concept and evaluation test rig.

  • Evaluate ACC kinematic system and actuator response and accuracy under engine simulated thermal and pressure conditions to 1200 °F and 120 psi.
  • Evaluate clearance sensor response and accuracy. Capacitance and microwave sensors being evaluated.
  • Measure ACC system seal leakage and wear performance and identify mitigation strategies.
  • Other factors to be investigated include:
    • Actuator stroke, rate, accuracy, and repeatability
    • System concentricity and synchronicity
    • Component wear
    • Secondary seal leakage
Simulated Take-off Engine Clearance Transient
Above: Simulated Take-off Engine Clearance Transient*. (Click image or link to view enlarged graph)

*From NASA/CP_2007-214995

+ Return to the branch research page...
Point of Contact
Dr. Bruce Steinetz
View a list of published NASA reports
+ View related publications
Related Facilities
Learn more about our Aerospace Seals Facilities
+ View Facility Listing
NASA Seals and Secondary Flows Symposium

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

Open to OEM'S and vendors
U.S. citizens and permanent legal residents (green card holders) only

Ohio Aerospace Institute Link to non-NASA website

GRC (Google Maps) Link to non-NASA website
Map to GRC (PDF)
Local food/lodging (PDF)

Download Workshop Papers
Get Adobe Acrobat Reader


+ Freedom of Information Act
+ NASA Web Privacy Policy and Important Notices
NASA - National Aeronautics and Space Administration
NASA Official: Ajay K. Misra
+ Web Curator
+ Contact NASA
Last Updated: November 4, 2013