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Enhanced Design of Turbo-jet LPT by Separation Control Using Phased Plasma ActuatorsThis work deals with the documentation and control of flow separation that occurs over turbine blades in the low-pressure turbine stage at low Reynolds numbers that exist at high altitude cruise. We utilize a specially constructed linear cascade that is designed to study the flow field over a generic LPT cascade consisting of Pratt & Whitney 'Pak B' shaped blades. This facility was constructed under a previous one-year NASA Glenn RC initiative. The center blade in the cascade is instrumented to measure the surface pressure coefficient distribution. Optical access allows two-component LDV measurement for boundary layer profiles. Experimental conditions have been chosen to give a range of chord Reynolds numbers from 10 to 100K, and a range of free-stream turbulence levels from u'/U(sub infinity)= 0.08 to 3 percent. The surface pressure measurements were used to define a region of separation and reattachment that depend on the free-stream conditions. The location of separation was found to be relatively insensitive to the experimental conditions. However, reattachment location was very sensitive to the turbulence level and Reynolds number. Excellent agreement was found between the measured pressure distributions and predictions from Euler and RANS simulations. Two-component LDV measurements are presently underway to document the mean and fluctuating velocity components in the boundary layer over the center blade for the range of experimental conditions. The fabrication of the plasma actuator is underway. These are designed to produce either streamwise vortices, or a downstream-directed wall jet. A precursor experiment for the former approach was performed with an array of vortex generators placed just upstream of the separation line. These led to reattachment except for the lowest Reynolds number. Progress has also been made on the proposed concept for a laterally moving wake. This involved constructing a smaller wind tunnel and molding an array of symmetric airfoils to form an array. Following its development, it will be scaled up and used to introduce lateral moving wakes upstream up the Pak-B cascade.
Document ID
20030056634
Acquisition Source
Headquarters
Document Type
Contractor Report (CR)
Authors
Ashpis, David (NASA Glenn Research Center Cleveland, OH, United States)
Corke, Thomas C. (Notre Dame Univ. IN, United States)
Thomas, Flint O. (Notre Dame Univ. IN, United States)
Date Acquired
September 7, 2013
Publication Date
April 1, 2003
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
E-13856
NASA/CR-2003-212294
NAS 1.26:212294
Funding Number(s)
CONTRACT_GRANT: NCC3-935
WORK_UNIT: WU 708-87-23
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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