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Research Papers

Time-Resolved Heat Transfer and Surface Pressure Measurements for a Fully Cooled Transonic Turbine Stage

[+] Author and Article Information
Jeremy B. Nickol

Gas Turbine Laboratory,
The Ohio State University,
Columbus, OH 43235
e-mail: nickol.10@osu.edu

Randall M. Mathison

Gas Turbine Laboratory,
The Ohio State University,
Columbus, OH 43235
e-mail: mathison.4@osu.edu

Malak F. Malak

Engineering & Technology,
Honeywell Aerospace,
Phoenix, AZ 85072
e-mail: malak.malak@honeywell.com

Rajiv Rana

Engineering & Technology,
Honeywell Aerospace,
Phoenix, AZ 85072

Jong S. Liu

Engineering & Technology,
Honeywell Aerospace,
Phoenix, AZ 85072
e-mail: jong.liu@honeywell.com

1Retired.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received December 16, 2014; final manuscript received February 10, 2015; published online April 15, 2015. Editor: Ronald Bunker.

J. Turbomach 137(9), 091009 (Sep 01, 2015) (11 pages) Paper No: TURBO-14-1318; doi: 10.1115/1.4029950 History: Received December 16, 2014; Revised February 10, 2015; Online April 15, 2015

The flow field in axial gas turbines is driven by strong unsteady interactions between stationary and moving components. While time-averaged measurements can highlight many important flow features, developing a deeper understanding of the complicated flows present in high-speed turbomachinery requires time-accurate measurements that capture this unsteady behavior. Toward this end, time-accurate measurements are presented for a fully cooled transonic high-pressure turbine stage operating at design-corrected conditions. The turbine is run in a short-duration blowdown facility with uniform, radial, and hot streak vane-inlet temperature profiles as well as various amounts of cooling flow. High-frequency response surface pressure and heat-flux instrumentation installed in the rotating blade row, stator vane row, and stationary outer shroud provide detailed measurements of the flow behavior for this stage. Previous papers have reported the time-averaged results from this experiment, but this paper focuses on the strong unsteady phenomena that are observed. Heat-flux measurements from double-sided heat-flux gauges (HFGs) cover three spanwise locations on the blade pressure and suction surfaces. In addition, there are two instrumented blades with the cooling holes blocked to isolate the effect of just blade cooling. The stage can be run with the vane and blade cooling flow either on or off. High-frequency pressure measurements provide a picture of the unsteady aerodynamics on the vane and blade airfoil surfaces, as well as inside the serpentine coolant supply passages of the blade. A time-accurate computational fluid dynamics (CFD) simulation is also run to predict the blade surface pressure and heat-flux, and comparisons between prediction and measurement are given. It is found that unsteady variations in heat-flux and pressure are stronger at low to midspan and weaker at high span, likely due to the impact of secondary flows such as the tip leakage flow. Away from the tip, it is seen that the unsteady fluctuations in pressure and heat-flux are mostly in phase with each other on the suction side, but there is some deviation on the pressure side. The flow field is ultimately shown to be highly three-dimensional, as the movement of high heat transfer regions can be traced in both the chord and spanwise directions. These measurements provide a unique picture of the unsteady flow physics of a rotating turbine, and efforts to better understand and model these time-varying flows have the potential to change the way we think about even the time-averaged flow characteristics.

Copyright © 2015 by ASME
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References

Figures

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Fig. 1

Turbine rig located within the facility

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Fig. 2

Turbine stage cooling paths

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Fig. 3

Photograph of pressure and suction sides of a blade

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Fig. 4

Computational domain with boundary conditions

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Fig. 5

Temperature traces for the upper side of a HFG on the blade surface

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Fig. 6

Experimental and computational time-averaged pressure ratio and Stanton number for the blade surface at 50% span

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Fig. 7

Encoder average unsteady Stanton number and pressure ratio over the blade at 50% span

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Fig. 8

Encoder average unsteady Stanton number and pressure ratio over the blade at 93% span

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Fig. 9

Results at 50% span and +33% WD (suction side)

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Fig. 10

Results at 50% span and −27% WD (pressure side)

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Fig. 11

Results at 50% span and −62% WD (pressure side)

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Fig. 12

Results at 93% span and −21% WD (pressure side)

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Fig. 13

Results at 93% span and −76% WD (pressure side)

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Fig. 14

Results at 93% span and +67% WD (suction side)

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Fig. 15

Results at 93% span and +86% WD (suction side)

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Fig. 16

Stanton number at 12% and 50% span, −52% WD

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Fig. 17

CFD heat-flux contours of rotor hub and blade pressure side at various values of VP

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Fig. 18

Magnitudes of unsteady content at various frequencies at 50% span (blue) and 93% span (red)

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Fig. 19

Boundary layer temperature difference between odd and even vane passages for hot streak and uniform run at 50% span, −18% WD

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