The NASA/Honeywell Quiet High-Speed Fan (QHSF) was designed with aggressive goals for performance and noise reduction. During testing in NASA Glenn Research Center's 9- by 15-Foot Low-Speed Wind Tunnel, this forward-swept fan performed very well at design speed, and it also accomplished its goal of decreasing noise (6 dB measured) from the baseline fan used in current engines. However, an unexpected, severe flutter problem was encountered at part-speed conditions.
Honeywell and Glenn used the flutter analysis capability of the TURBO-AE code to redesign the QHSF. The TURBO-AE code was included in Honeywell's design cycle. During the redesign effort, more than 30 airfoil geometries were analyzed in the design-of-experiments approach and more than 600 TURBO-AE flutter analyses were performed. The redesigned QHSF II, which is predicted to be flutter-free throughout its operating range, is being fabricated and will be tested in Glenn's 9- by 15-ft wind tunnel in the near future. Engine validation of the TURBO-AE flutter predictions for the QHSF II will be conducted on Honeywell's AS-907 advanced technology demonstrator engine in 2005. This work contributes directly to NASA's 10-year goal of reducing noise in future aircraft by 50 percent (10 dB) from current levels. It also enables aircraft engine blade rows to be checked for flutter stability during design with realistic physics modeling, thus eliminating added costs ($5 to $30 million) and delays (1 to 3 months) in engine development due to unexpected flutter vibrations. If a flutter analysis tool such as TURBO-AE had been available during the original QHSF design effort, the entire QHSF redesign may have been avoided, with an estimated saving of $2.4 million. The flutter calculations described here were performed under a contract by University of Toledo researchers in collaboration with Glenn and Honeywell researchers. All of this work was funded by the Quiet Aircraft Technology project (Dr. Joseph Grady, project manager).
Glenn contact: Dr. Milind A. Bakhle, 216-433-6037, Milind.A.Bakhle@nasa.gov
University of Toledo contact: Dr. Rakesh Srivastava, 216-433-6045, Rakesh.Srivastava@grc.nasa.gov
Authors: Dr. Milind A. Bakhle and Dr. Rakesh Srivastava
Headquarters program office: OAT
Programs/Projects: QAT, QHSF
Last updated: January 18, 2005
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