A Nonlinear Model for Designing Herschel-Quincke Waveguide Arrays to Attenuate Shock Waves from Transonic Turbofan Engines

Award Information
Agency: National Aeronautics and Space Administration
Branch: N/A
Contract: NNL05AA75P
Agency Tracking Number: 042298
Amount: $69,892.00
Phase: Phase I
Program: SBIR
Awards Year: 2005
Solicitation Year: 2004
Solicitation Topic Code: A2.04
Solicitation Number: N/A
Small Business Information
2901 Prosperity Rd., Blacksburg, VA, 24060-6644
DUNS: 003220998
HUBZone Owned: Y
Woman Owned: N
Socially and Economically Disadvantaged: Y
Principal Investigator
 Jason Anderson
 Principal Investigator
 (540) 961-4401
 janderson@techsburg.com
Business Contact
 Tamara Murray
Title: Business Manager
Phone: (540) 961-4401
Email: tmurray@techsburg.com
Research Institution
N/A
Abstract
Techsburg is teaming with the Vibration and Acoustics Laboratory of Virginia Tech to propose a non-linear analytical tool for designing Herschel-Quincke (HQ) waveguide arrays for the purpose of attenuating upstream-propagating shock waves in a transonic turbofan engine inlet. Techsburg will be receiving endorsement and support for this research from the Goodrich Company who owns the HQ waveguide array concept. Thus far linear acoustic modeling has been used to design HQ waveguide arrays that have experimentally proven to be successful in attenuating far-field sound radiation from subsonic ducted fans. However, the large transonic turbofan engines used in most civil aviation aircraft today produce large amplitude bow shocks upstream of the fan rotor that nonlinearly scatter energy from the dominant BPF circumferential mode near the fan rotor to primarily lower engine order circumferential modes at the duct entrance, which produces the "buzz-saw" far-field acoustic signature. The non-linear design tool developed by Techsburg/Virginia Tech in Phase I will be used to design an optimal HQ waveguide array in Phase II that will be placed near the fan with the intention of attenuating the BPF circumferential mode in order to reduce scattered energy into lower engine orders that cause far-field "buzz-saw" noise.

* Information listed above is at the time of submission. *

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