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Lewis-Developed Seals Serve General Electric
Technology Needs
Advanced aircraft engines require high-temperature, flexible seals to prevent backflow of high-
temperature combustion gases. To meet this critical need, the NASA Lewis Research Center's
Structural Dynamics Branch developed a line of hybrid braided-rope seals capable of high-temperature, high-pressure operation, while conforming to and sealing complex engine structures
that distort during operation. The seals operate at temperatures several hundred degrees above
competing graphite seals. Another benefit is that they do not have the health hazards associated
with competing asbestos-based seals that are now banned for most uses.
Being acquainted with Lewis' high-temperature seal development, the General Electric Company
(GE) worked with researchers in the Structural Dynamics Branch to determine if the braided rope
seals could be used as a high-temperature compliant seal/mount for components in one of GE's
advanced Integrated High Performance Turbine Engine Technology (IHPTET) demonstrator
tests. These tests were sponsored by the U.S. Air Force Wright Laboratory's Aero Propulsion
and Power Directorate and the U.S. Navy. GE researchers asked Lewis for assistance in solving a
difficult sealing problem. Within GE's rapid turnaround requirement of 4 months, Lewis
successfully developed, tested, and delivered the necessary seals. These seals are fabricated of a
high-temperature, flow-resistant core of ceramic fibers overbraided with an abrasion-resistant
sheath made of high-temperature superalloy wires.
Advanced Alloy Development
For a number of years, GE has been developing advanced alloys for high-temperature turbine
blades and vanes. Through GE's considerable development efforts, complemented by the efforts
of Lewis' Materials and Structures Division researchers, these advanced, high-temperature,
oxidation-resistant intermetallic alloys have evolved to sufficient technical maturity to be
considered for the IHPTET program.
Vane/Seal Tests
Feasibility testing of the vane/seal system demonstrated that the compliant seal/mount showed
promise in reducing thermal stresses that develop in the engine components exposed to
combustion temperatures, thereby increasing life. The advanced alloy vanes and the compliant
seal/mount were then successfully tested (last quarter of 1995) in a Joint Technology Advanced
Gas Generator (JTAGG) engine, meeting stringent IHPTET phase I and temperature goals. The
hardware ran at temperatures several hundred degrees Fahrenheit above conventional technology
vane/seal-mount systems. These tests confirmed the viability of the vane and compliant
seal/mount approach, paving the way for possible use in future advanced military engines.
This project is an example of how, by working with our industry counterparts, Government
researchers can successfully transfer Government-developed technology to private industry. It is
rewarding to have a major company recognize that Government researchers provide unique
capabilities--solving technically challenging problems and developing critical components in
short time periods.
Bibliography
Steinetz, B.M., et al.: High Temperature Braided Rope Seals for Static Sealing Applications. To
be published as a NASA TM, 1996.
Lewis contact: Dr. Bruce M. Steinetz; (216) 433-3302
Headquarters program office: OA
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Last updated April 16, 1996
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