Title page for ETD etd-07172005-183729


Type of Document Master's Thesis
Author Halasz, Christopher
URN etd-07172005-183729
Title Advanced Trailing Edge Blowing Concepts for Fan Noise Control: Experimental Validation
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Burdisso, Ricardo A. Committee Chair
Johnson, Martin E. Committee Member
Ng, Fai Committee Member
Keywords
  • acoustic liners
  • interaction noise spectra
  • trailing edge blowing
  • flow control
Date of Defense 2005-06-20
Availability unrestricted
Abstract
This thesis documents trailing edge blowing research performed to reduce rotor / stator interaction noise in turbofan engines. The existing technique of filling every velocity deficit requires a large amount of air and is therefore impractical. The purpose of this research is to investigate new blowing configurations in order to achieve noise reduction with lesser amounts of air. Using the new configurations air is not injected into every fan blade, but is instead varied circumferentially. For example, blowing air may be applied to alternating fan blades. This type of blowing configuration both reduces the amount of air used and changes the spectral shape of the tonal interaction noise. The original tones at the blade passing frequency and its harmonics are reduced and new tones are introduced between them. This change in the tonal spectral shape increases the performance of acoustic liners used in conjunction with trailing edge blowing. This thesis presents numerical predictions performed to estimate the sound power reductions due to these concepts, as well as experimental results taken on the ANCF rig at NASA Glenn for validation purposes. The results show that the new concepts are successful in increasing the efficiency of trailing edge blowing.
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