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Research Papers: Fundamental Issues and Canonical Flows

Numerical and Experimental Investigation of Aerodynamic Performance for a Straight Turbine Cascade With a Novel Partial Shroud

[+] Author and Article Information
Yan Liu

School of Energy and Power Engineering,
Dalian University of Technology,
No. 2 Linggong Road,
Ganjingzi District,
Dalian 116024, China
e-mail: yanliu@dlut.edu.cn

Tian-Long Zhang

School of Energy and Power Engineering,
Dalian University of Technology,
No. 2 Linggong Road,
Ganjingzi District,
Dalian 116024, China
e-mail: zhtl369@163.com

Min Zhang

School of Energy and Power Engineering,
Dalian University of Technology,
No. 2 Linggong Road,
Ganjingzi District,
Dalian 116024, China
e-mail: modest_zm@126.com

Meng-Chao Zhang

School of Energy and Power Engineering,
Dalian University of Technology,
No. 2 Linggong Road,
Ganjingzi District,
Dalian 116024, China
e-mail: mczdlut@163.com

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received February 6, 2015; final manuscript received September 1, 2015; published online October 20, 2015. Assoc. Editor: D. Keith Walters.

J. Fluids Eng 138(3), 031206 (Oct 20, 2015) (10 pages) Paper No: FE-15-1094; doi: 10.1115/1.4031556 History: Received February 06, 2015; Revised September 01, 2015

A comparative experimental and numerical analysis is carried out to assess the aerodynamic performance of a novel partial shroud in a straight turbine cascade. This partial shroud is designed as a combination of winglet and shroud. A plain tip is employed as a baseline case. A pure winglet tip is also studied for comparison. Both experiments and predictions demonstrate that this novel partial shroud configuration has aerodynamic advantages over the pure winglet arrangement. Predicted results show that, relative to the baseline blade with a plain tip, using the partial shroud can lead to a reduction of 20.89% in the mass-averaged total pressure coefficient on the upper half-span of a plane downstream of the cascade trailing edge and 16.53% in the tip leakage mass flow rate, whereas the pure winglet only decreases these two performance parameters by 11.36% and 1.32%, respectively. The flow physics is explored in detail to explain these results via topological analyses. The use of this new partial shroud significantly affects the topological structures and total pressure loss coefficients on various axial cross sections, particularly at the rear part of the blade passage. The partial shroud not only weakens the tip leakage vortex (TLV) but also reduces the strength of passage vortex near the casing (PVC) endwall. Furthermore, three partial shrouds with width-to-pitch ratios of 3%, 5%, and 7% are considered. With an increase in the width of the winglet part, improvements in aerodynamics and the tip leakage mass flow rate are limited.

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Figures

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Fig. 1

Three configurations studied: (a) case 1, a plain tip, (b) case 2, a double-side winglet tip, and (c) cases 3–5, a novel partial shroud tip

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Fig. 2

Experimental facility: (a) schematic of the cascade and (b) test rig

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Fig. 3

Computational grid of the partial shroud (case 3)

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Fig. 4

Vortex core structures in case 1

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Fig. 5

Contours of Cpt and secondary flow streamlines on the measurement plane: (a) CFD and (b) EXP.

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Fig. 6

Comparison of contours of Cpt and streamlines of secondary flow on the measurement plane for cases 2 and 3: (a) case 2, CFD, (b) case 3, CFD, and (c) case 3, EXP.

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Fig. 7

Comparison of predicted mass-averaged Cpt for cases 1–3 over the upper half-span of the measurement plane

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Fig. 8

Predicted tip leakage mass flow rates CD for cases 1–3

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Fig. 9

Predicted Cpt and secondary flow fields on different cross section planes for cases 1 and 3: (a) plane 1, case 1, (b) plane 2, case 1, (c) plane 3, case 1, (d) plane 4, case 1, (e) plane 1, case 3, (f) plane 2, case 3, (g) plane 3, case 3, and (h) plane 4, case 3

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Fig. 10

Vortex structures on different axial cross sections for (a) case 1 and (b) case 3

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Fig. 11

Predicted mass-averaged Cpt over the upper half-span of different transverse planes

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Fig. 12

Contours of Cpt and streamlines of secondary flow on the 1.36Cax plane for cases 4 and 5: (a) case 4, CFD, (b) case 4, EXP., and (c) case 5, CFD

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Fig. 13

Pitchwise-averaged Cpt for cases 1 and 3–5 on the 1.36Cax plane

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Fig. 14

Pitchwise-averaged yaw angles for cases 1 and 3–5 on the 1.36Cax plane

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Fig. 15

Predicted mass-averaged Cpt over the upper half-span of the 1.36Cax plane for cases 1–5

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Fig. 16

Predicted contours of static pressure coefficient on the blade tip surface: (a) case 1, (b) case 3, (c) case 4, and (d) case 5

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Fig. 17

Distributions of static pressure coefficients on the blade surface at 97.5%h for cases 1 and 3–5

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Fig. 18

Predicted leakage mass flow rates CD for cases 1–5

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