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TECHNICAL PAPERS

Aerodynamic Losses of a Cambered Turbine Vane: Influences of Surface Roughness and Freestream Turbulence Intensity

[+] Author and Article Information
Qiang Zhang

Convective Heat Transfer Laboratory, Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112-9208

Phillip M. Ligrani1

Convective Heat Transfer Laboratory, Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112-9208

1

To whom correspondence should be addressed.

J. Turbomach 128(3), 536-546 (Jan 23, 2006) (11 pages) doi:10.1115/1.2185125 History: Received January 20, 2006; Revised January 23, 2006

The effects of surface roughness and freestream turbulence level on the aerodynamic performance of a turbine vane are experimentally investigated. Wake profiles are measured with three different freestream turbulence intensity levels (1.1%, 5.4%, and 7.7%) at two different locations downstream of the test vane trailing edge (1 and 0.25 axial chord lengths). Chord Reynolds number based on exit flow conditions is 0.9×106. The Mach number distribution and the test vane configuration both match arrangements employed in an industrial application. Four combered vanes with different surface roughness levels are employed in this study. Effects of surface roughness on the vane pressure side on the profile losses are relatively small compared to suction side roughness. Overall effects of turbulence on local wake deficits of total pressure, Mach number, and kinetic energy are almost negligible in most parts of the wake produced by the smooth test vane, except that higher freestream losses are present at higher turbulence intensity levels. Profiles produced by test vanes with rough surfaces show apparent lower peak values in the center of the wake. Integrated aerodynamic losses and area-averaged loss coefficient YA are also presented and compared to results from other research groups.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 1

Schematic diagram of the test section

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Figure 2

Test section vanes with rough surfaces: (a) Vane with uniform roughness and (b) vane with variable roughness on pressure side

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Figure 3

Comparison of smooth vane wake total pressure loss coefficient profile with similar data from Ames and Plesniak (22)

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Figure 4

Three-dimensional Wyko profilometry traces of portions of the rough surfaces: (a) Simulated rough surface with small-sized roughness elements and (b) rough surface from the pressure side of a turbine vane with particulate deposition from a utility power engine

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Figure 5

Mach number distributions along the test vane

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Figure 6

Normalized local total pressure loss profiles measured one axial chord length downstream of the test vane with various surface roughness for Tu=1.1%

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Figure 11

Comparison of IAL as dependent on normalized equivalent sand-grain roughness size for different inlet turbulence intensity levels, as measured at two different locations downstream of the test vane trailing edge (1 and 0.25 axial chord lengths)

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Figure 12

Comparison of normalized IAL as dependent on normalized equivalent sand-grain roughness size for different inlet turbulence intensity levels obtained one axial length downstream of the turbine vane

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Figure 13

Comparison of area averaged loss coefficients measured in normal planes 0.25cx downstream of the vane, with predictions from Boyle (21)

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Figure 10

Normalized local total pressure losses profiles measured 0.25 axial chord length downstream of the test vane: (a) ks∕cx=0.00108, (b) ks∕cx=0.00258, and (c) variable roughness

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Figure 8

Normalized local total pressure losses. Profiles measured with different turbulence intensity levels one axial chord length downstream of the test vane with a smooth surface.

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Figure 7

Profiles measured 0.25 axial chord length downstream of the test vane with various surface roughness for Tu=5.4%: (a) Normalized local total pressure losses, (b) normalized local Mach numbers, and (c) normalized local kinetic energy

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Figure 9

Profiles measured at 0.25 axial chord length downstream of the test vane with a smooth surface: (a) Normalized local total pressure losses, (b) normalized local Mach numbers, and (c) normalized local kinetic energy

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