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Research Papers

Measurements of Losses and Reynolds Stresses in the Secondary Flow Downstream of a Low-Speed Linear Turbine Cascade

[+] Author and Article Information
G. D. MacIsaac

Chancellor’s Professor and Pratt & Whitney Canada Research Fellowgdmacisa@connect.carleton.caDepartment of Mechanical and Aerospace Engineering,  Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canadagdmacisa@connect.carleton.ca

S. A. Sjolander

Chancellor’s Professor and Pratt & Whitney Canada Research Fellowssjoland@mae.carleton.caDepartment of Mechanical and Aerospace Engineering,  Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canadassjoland@mae.carleton.ca

T. J. Praisner

Turbine Aerodynamics,  United Technologies, Pratt & Whitney Aircraft, 400 Main Street, MS 169-29, East Hartford, CT 06108thomas.praisner@pw.utc.com

J. Turbomach 134(6), 061015 (Sep 04, 2012) (12 pages) doi:10.1115/1.4003839 History: Received January 14, 2011; Revised January 27, 2011; Published September 04, 2012; Online September 04, 2012

Experimental measurements of the mean and turbulent flow field were preformed downstream of a low-speed linear turbine cascade. The influence of turbulence on the production of secondary losses is examined. Steady pressure measurements were collected using a seven-hole pressure probe and the turbulent flow quantities were measured using a rotatable x-type hotwire probe. Each probe was traversed downstream of the cascade along planes positioned at three axial locations: 100%, 120%, and 140% of the axial chord (Cx ) downstream of the leading edge. The seven-hole pressure probe was used to determine the local total and static pressure as well as the three mean velocity components. The rotatable x-type hotwire probe, in addition to the mean velocity components, provided the local Reynolds stresses and the turbulent kinetic energy. The axial development of the secondary losses is examined in relation to the rate at which mean kinetic energy is transferred to turbulent kinetic energy. In general, losses are generated as a result of the mean flow dissipating kinetic energy through the action of viscosity. The production of turbulence can be considered a preliminary step in this process. The measured total pressure contours from the three axial locations (1.00, 1.20, and 1.40Cx ) demonstrate the development of the secondary losses. The peak loss core in each plane consists mainly of low momentum fluid that originates from the inlet endwall boundary layer. There are, however, additional losses generated as the flow mixes with downstream distance. These losses have been found to relate to the turbulent Reynolds stresses. An examination of the turbulent deformation work term demonstrates a mechanism of loss generation in the secondary flow region. The importance of the Reynolds shear stresses to this process is explored in detail.

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Copyright © 2012 by American Society of Mechanical Engineers
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Figures

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Figure 1

Test section schematic

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Figure 11

Total pressure coefficient (CP 0 ), deformation work term (Ψi,j ), velocity gradient (∂U¯j′/∂xj′), and Reynolds stress (ui′uj′¯) at z/h = 0.5, 0.19, and 0.05 at 1.20Cx

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Figure 12

Total pressure coefficient (CP 0 ), deformation work term (Ψi,j ), velocity gradient (∂U¯j′/∂xj′), and Reynolds stress (ui′uj′¯) at z/h = 0.5, 0.19, and 0.08 at 1.40Cx

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Figure 2

Cascade nomenclature showing the cascade and mean flow coordinate systems

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Figure 3

Inlet boundary layer profile measured at −1.20Cx and 0.25, 0.50, and 0.75y/s

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Figure 4

Pitchwise variation of turbulence intensity and Reynolds stresses at −1.90Cx and z/h = 0.5

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Figure 5

Blade surface static pressure distribution at z/h = 0.05 and 0.5

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Figure 6

Total pressure coefficient (CP 0 ) floods at (a) 1.00Cx , (b) 1.20Cx , and (c) 1.40Cx

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Figure 7

Streamwise vorticity coefficient (Cωs) floods with contour lines of total pressure coefficient (CP 0 ) and secondary velocity vectors at (a) 1.00Cx , (b) 1.20Cx , and (c) 1.40Cx

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Figure 8

Integrated total pressure, secondary kinetic energy, turbulent kinetic energy coefficients, and energy summation at 1.00Cx , 1.20Cx , and 1.40Cx

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Figure 9

Floods of local turbulence intensity (Tuloc ) with contour lines of total pressure coefficient (CP 0 ) at (a) 1.00Cx , (b) 1.20Cx , and (c) 1.40Cx

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Figure 10

Floods of the deformation work term Ψi,j with contour lines of total pressure coefficient and the secondary velocity vectors at (a) 1.20Cx and (b) 1.40Cx

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