Title page for ETD etd-4241161974360


Type of Document Dissertation
Author Leitch, Thomas A.
Author's Email Address tleitch@vt.edu
URN etd-4241161974360
Title Reduction of Unsteady Rotor-Stator Interaction Using Trailing Edge Blowing
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Burdisso, Ricardo A.
Dancey, Clinton L.
Ng, W. F. Committee Chair
Keywords
  • Trailing Edge Blowing
  • Aeroacoustic
  • Noise
  • Turbomachinery
Date of Defense 1997-01-16
Availability unrestricted
Abstract
An aeroacoustic investigation was performed to assess the effects of

adding mass flow at the trailing edges of four stators upstream of an

aircraft engine simulator. By using trailing edge blowing to minimize the

shed wakes of the stators, the flow into the rotor was made more

uniform. In these experiments a reduced number of stators (four) was

used in a 1/14 scale model inlet which was coupled to a 4.1 in (10.4

cm) turbofan engine simulator with 18 rotors and 26 downstream

stators. This study is a preliminary step toward a more in depth

investigation of using trailing edge blowing to reduce unsteady

rotor-stator interaction. Steady-state measurements of the

aerodynamic flow field and acoustic far field were made in order to

evaluate the aeroacoustic performance at three simulator speeds: 40%,

60%, and 88% of the design speed. The lowest test speed of 40%

design speed showed the most dramatic reduction in radiated noise.

Noise reductions as large as 8.9 dB in the blade passing tone were

recorded at 40% design speed, while a tone reduction of 5.5 dB was

recorded at 60% design speed. At 88% design speed a maximum tone

reduction of 2.6 dB was recorded. In addition, trailing edge blowing

reduced the overall sound pressure level in every case. For both the

40% design speed and the 60% design speed, the fan face distortion

was significantly reduced due to the trailing edge blowing. The addition

of trailing edge blowing from the four upstream stators did not change

the total pressure ratio, and the mass flow added by the blowing was

approximately 1%. The results of these experiments clearly

demonstrate that blowing from the trailing edges of the stators is

effective in reducing unsteady rotor-stator interaction and the

subsequent forward radiated noise.

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