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TECHNICAL PAPERS

Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Intermittency Behavior Along the Suction Surface of a Low Pressure Turbine Blade

[+] Author and Article Information
M. T. Schobeiri, B. Öztürk

Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University, College Station, TX 77843-3123

David E. Ashpis

National Aeronautics and Space Administration, John H. Glenn Research Center at Lewis Field, Cleveland, OH 44135

J. Turbomach 129(1), 92-107 (Feb 01, 2005) (16 pages) doi:10.1115/1.2219762 History: Received October 01, 2004; Revised February 01, 2005

The paper experimentally studies the effects of periodic unsteady wake flow and Reynolds number on boundary layer development, separation, reattachment, and the intermittency behavior along the suction surface of a low pressure turbine blade. Extensive unsteady boundary layer experiments were carried out at Reynolds numbers of 110,000 and 150,000 based on suction surface length and exit velocity. One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The analysis of the experimental data reveals details of boundary layer separation dynamics which is essential for understanding the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds numbers. To provide a complete picture of the transition process and separation dynamics, extensive intermittency analysis was conducted. Ensemble-averaged maximum and minimum intermittency functions were determined, leading to the relative intermittency function. In addition, the detailed intermittency analysis was aimed at answering the question as to whether the relative intermittency of a separated flow fulfills the universality criterion.

Copyright © 2007 by American Society of Mechanical Engineers
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References

Figures

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Figure 5

Distribution of time-averaged velocities along the suction surface for steady case Ω=0(SR=∞) and unsteady cases Ω=1.59(SR=160mm) and Ω=3.18(SR=80mm) at Re=110,000

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Figure 6

Distribution of time-averaged velocity fluctuations along the suction surface for steady case Ω=0(SR=∞) and unsteady cases Ω=1.59(SR=160mm) and Ω=3.18(SR=80mm) at Re=110,000

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Figure 9

Distribution of the ensemble-averaged velocity development along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=1.59(SR=160mm) and Re=110,000

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Figure 10

Distribution of the ensemble-averaged velocity development along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=3.18(SR=80mm) and Re=110,000

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Figure 11

Distribution of the ensemble-averaged velocity development along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=1.59(SR=160mm) and Re=150,000

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Figure 12

Distribution of the ensemble-averaged velocity development along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=3.18(SR=80mm) and Re=150,000

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Figure 13

Ensemble-averaged velocity contours along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=1.59(SR=160mm), Re=110,000

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Figure 14

Ensemble-averaged velocity contours along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=3.18(SR=80mm), Re=110,000

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Figure 15

Ensemble-averaged velocity contours along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=1.59(SR=160mm), Re=150,000

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Figure 16

Ensemble-averaged velocity contours along the suction surface for different s∕s0 with time t∕τ as parameter for Ω=3.18(SR=80mm), Re=150,000

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Figure 19

Relative intermittency as a function of s∕s0 for unsteady frequency of Ω=1.59(SR=160mm) at (a) y=0.858mm, (b) y=0.996mm, (c) y=5.3mm, and (d) y=9.3mm at Re=110,000

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Figure 20

Maximum, minimum, and time-averaged intermittency as a function of s∕s0 at different lateral positions for steady case Ω=0(SR=∞) and unsteady cases Ω=1.59(SR=160mm) and Ω=3.18(SR=80mm) at Re=110,000

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Figure 1

Turbine cascade research facility with the components and the adjustable test section

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Figure 3

Turbine cascade research facility with three-axis traversing system

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Figure 4

Static pressure distributions at two different Re numbers and reduced frequencies Ω=0, 1.59, 3.18 (no rod, 160, 80mm), SS=separation start, SE=separation end

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Figure 7

Distribution of time-averaged velocity distributions along the suction surface for steady case Ω=0(SR=∞) and unsteady cases Ω=1.59(SR=160mm) and Ω=3.18(SR=80mm) at Re=150,000

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Figure 8

Distribution of time-averaged fluctuation velocities along the suction surface for steady case Ω=0(SR=∞) and unsteady cases Ω=1.59(SR=160mm) and Ω=3.18(SR=80mm) at Re=150,000

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Figure 17

Calculation of ensemble-averaged intermittency function from instantaneous velocities for Ω=1.725 at y=0.720mm

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Figure 18

Ensemble-averaged intermittency factor in the temporal-spatial domain at different y positions for Ω=1.59(SR=160mm) and Ω=3.18(SR=80mm)

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