Title page for ETD etd-11272007-004310


Type of Document Master's Thesis
Author Perry, Michael
URN etd-11272007-004310
Title The Effect of Freestream Turbulence on Separation at Low Reynolds Numbers in a Compressor Cascade
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
O'Brien, Walter F. Jr. Committee Chair
Dancey, Clinton L. Committee Member
Paul, Mark R. Committee Member
Wicks, Alfred L. Committee Member
Keywords
  • Turbulence Grid
  • Separation
  • Compressor Cascade
  • Hotwire Anemometer
  • Aerodynamic Loss
  • Boundary Layer Transition
  • Oil Flow Visualization
Date of Defense 2007-11-15
Availability unrestricted
Abstract
A parametric study was performed to observe and quantify the effect of varying turbulence intensities on separation and performance in a compressor cascade at low Reynolds numbers. Tests were performed at 25o and 37.5o stagger angle, negative and positive angles of incidence up until the point of full stall, Reynolds numbers from 6 x 104 to 12.5 x 104, and turbulence intensities from approximately 0.7% – 8%. Additionally, oil flow techniques were combined with static tap data to visualize the boundary layer characteristics at various test conditions. The overall performance of the cascade was presented and evaluated through mass-averaged total pressure loss coefficients.

The results of the study showed that the best efficiency (lowest pressure loss coefficient) was determined by separation characteristics for any angle of attack. While adding turbulence generally delayed separation, in some cases, adding turbulence to a separated airfoil resulted in decreased performance. Very similar separation characteristics were observed for the full range of Reynolds numbers and stagger, with the higher stagger setting giving slightly better performance. It was shown that a large percentage of total pressure losses can be recovered by applying the appropriate turbulence intensity at any angle of attack, which is relevant to possibilities for active control of such flows.

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