GLTRS--Glenn
TITLE AND SUBTITLE:
Evaluation of High Temperature Knitted Spring Tubes for Structural Seal Applications

AUTHOR(S):
Shawn C. Taylor, Jeffrey J. DeMange, Patrick H. Dunlap, Jr., and Bruce M. Steinetz

REPORT DATE:
September 2004

FUNDING NUMBERS:
WBS-22-794-40-4V

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-14679

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-2004-213183
AIAA-2004-3890

SUPPLEMENTARY NOTES:
Prepared for the 40th Joint Propulsion Conference and Exhibit cosponsored by AIAA, ASME, SAE, and ASEE, Fort Lauderdale, Florida, July 11-14, 2004. Shawn C. Taylor, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106-4901; Jeffrey J. DeMange, University of Toledo, 2801 W. Bancroft Street, Toledo, Ohio 43606; Patrick H. Dunlap, Jr., and Bruce M. Steinetz, Glenn Research Center. Responsible person, Shawn C. Taylor, organization code 5950, 216-433-6374.

ABSTRACT:
Control surface seals are crucial to current and future space vehicles, as they are used to seal the gaps surrounding body flaps, elevons, and other actuated exterior surfaces. During reentry, leakage of high temperature gases through these gaps could damage underlying lower temperature structures such as rudder drive motors and mechanical actuators, resulting in impaired vehicle control. To be effective, control surface seals must shield lower temperature structures from heat transfer by maintaining sufficient resiliency to remain in contact with opposing sealing surfaces through multiple compression cycles. The current seal exhibits significant loss of resiliency after a few compression cycles at elevated temperatures (i.e., 1900 °F) and therefore would be inadequate for advanced space vehicles. This seal utilizes a knitted Inconel X-750 spring tube as its primary resilient element. As part of a larger effort to enhance seal resiliency, researchers at the NASA Glenn Research Center performed high temperature compression testing (up to 2000 °F) on candidate spring tube designs employing material substitutions and modified geometries. These tests demonstrated significant improvements in spring tube resiliency (5.5x better at 1750 °F) through direct substitution of heat treated Rene 41 alloy in the baseline knit design. The impact of geometry modification was minor within the range of parameters tested, however trends did suggest that moderate resiliency improvements could be obtained by optimizing the current spring tube geometry.

SUBJECT TERMS:
Seals; Resiliency; Design; Test; High temperature

NUMBER OF PAGES:
26

PDF AVAILABLE FROM URL:
2004/TM-2004-213183.pdf ( 6,647 KB )
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