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Research Papers

Film Cooling on the Geometrically Modified Trailing Edge Model of Gas Turbine Blade

[+] Author and Article Information
Zifeng Yang

Wright State University,
Dayton, OH 45435
e-mail: zifeng.yang@wright.edu

Mark Johnson

Wright State University,
Dayton, OH 45435
e-mail: mark.johnson@wright.edu

Natalia Posada

US Air Force Research Laboratory,
Wright Patterson AFB,
OH 45433
e-mail: natalia.posada.1@us.af.mil

Shichuan Ou

US Air Force Research Laboratory,
Wright Patterson AFB,
OH 45433
e-mail: shichuan.ou@gmail.com

Rolf Sondergaard

US Air Force Research Laboratory,
Wright Patterson AFB,
OH 45433
e-mail: rolf.sondergaard@us.af.mil

1Corresponding author.

Manuscript received August 8, 2018; final manuscript received May 31, 2019; published online July 22, 2019. Assoc. Editor: Dr. David G. Bogard. The work was authored in part by a U.S. Government employee in the scope of his/her employment. ASME disclaims all interest in the U.S. Government’s contribution.

J. Turbomach 141(9), 091012 (Jul 22, 2019) (13 pages) Paper No: TURBO-18-1193; doi: 10.1115/1.4043968 History: Received August 08, 2018; Accepted May 31, 2019

The objective of this study is to examine the effect of the geometrical modification of the land on the overall film cooling effectiveness on the cutback region of a turbine blade model. A room-temperature experiment was conducted, in which nitrogen serves as the cooling stream, and the mainstream flow is air. The adiabatic film cooling effectiveness was mapped employing the pressure-sensitive paint (PSP) technique. Data was acquired at five different blowing ratios (from 0.45 to 1.65) for both the baseline and the modified model. Detailed film cooling effectiveness from PSP measurements in correlation with the flow map in streamwise and spanwise planes from particle image velocimetry (PIV) measurements was performed, characterizing the effect of rounding the edges of the lands. The results show that the rounded edges enable the coolant flow to reach the top surface of the land area more readily, especially at low blowing ratios. Superior coolant coverage on the land surface observed in the PSP measurements are well correlated with the PIV measurements. At the high blowing ratio of 1.65, the round edge of the lands helps regulate the mixing between the coolant and mainstream flows, therefore the film cooling effectiveness in the slot region is also improved.

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References

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Figures

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Fig. 1

Baseline model in the test section and the redesign with rounded corners and edges: (a) baseline sharp corner model in the test section, (b) modified trailing edge model, and (c) dimension of the baseline model

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Fig. 2

Turbulence velocity spectrum of the coolant flow for BR = 0.45

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Fig. 3

Experimental setup for PSP and PIV measurements: (a) PSP setup and (b) PIV setup

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Fig. 4

Overall view of the PIV measurement planes crossing the model

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Fig. 5

In-plane velocity vectors due to an out-of-plane movement (1 mm)

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Fig. 6

Film cooling effectiveness distribution at different blowing ratios for the baseline model (left column) and the modified model (right column): (a) baseline model, BR = 0.45; (b) modified model, BR = 0.45; (c) baseline model, BR = 0.65; (d) modified model, BR = 0.65; (e) baseline model, BR = 0.90; (f) modified model, BR = 0.90; (g) baseline model, BR = 1.20; (h) modified model, BR = 1.20; (i) baseline model, BR = 1.65; and (j) modified model, BR = 1.65

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Fig. 7

Averaged film cooling effectiveness: (a) spanwise averaged in the slot, (b) spanwise averaged on the land surface, (c) overall averaged in the slot, and (d) overall averaged on the land surface

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Fig. 8

Flow velocity field in spanwise plane for baseline model and modified model at BR = 0.45: (a) baseline model at X/H = 0.8, (b) modified model at X/H = 0.8, (c) baseline model at X/H = 4.0, (d) modified model at X/H = 4.0, (e) baseline model at X/H = 6.0, and (f) modified model at X/H = 6.0 (Note: the main flow feature was highlighted by the arrowed line superimposed on the vector field, 2 × 2 vectors were skipped from the image)

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Fig. 9

Diagram of the flow feature for low blow ratio

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Fig. 10

Flow velocity field in streamwise planes for the baseline model and the modified model at BR = 0.45: (a) baseline model at Z/H = 0, (b) modified model at Z/H = 0, (c) baseline model at Z/H = −2, and (d) modified model at Z/H = −2 (Note: 4 × 4 vectors were skipped from the image)

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Fig. 11

Flow velocity field in streamwise plane for the baseline model and the modified model at BR = 0.9: (a) baseline model at Z/H = 0, (b) modified model at Z/H = 0, (c) baseline model at Z/H = −2, and (d) modified model at Z/H = −2 (Note: 4 × 4 vectors were skipped from the image)

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Fig. 12

Flow velocity field in spanwise plane for the baseline model and the modified model at BR = 0.9: (a) baseline model at X/H = 0.8, (b) modified model at X/H = 0.8, (c) baseline model at X/H = 4.0, (d) modified model at X/H = 4.0, (e) baseline model at X/H = 6.0, and (f) modified model at X/H = 6.0 (Note: the main flow feature was highlighted by the arrowed line superimposed on the vector field)

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Fig. 13

Flow velocity field in streamwise plane for the baseline and the modified model at BR = 1.65: (a) baseline model at Z/H = 0, (b) modified model at Z/H = 0, (c) baseline model at Z/H = −2, and (d) modified model at Z/H = −2 (Note: 4 × 4 vectors were skipped from the image)

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Fig. 14

Flow velocity field in spanwise plane for the baseline model (left column) and the modified model (right column) at BR = 1.65: (a) baseline model at X/H = 0.8, (b) modified model at X/H = 0.8, (c) baseline model at X/H = 4.0, (d) modified model at X/H = 4.0, (e) baseline model at X/H = 6.0, and (f) modified model at X/H = 6.0 (Note: the main flow feature was highlighted by the arrowed line superimposed on the vector field)

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