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Research Papers: Flows in Complex Systems

Effect of Winglet-Shroud Tip With Labyrinth Seals on Aerodynamic Performance of a Linear Turbine Cascade

[+] Author and Article Information
Yan Liu

Key Laboratory of Ocean Energy Utilization and
Energy Conservation of Ministry of Education,
Dalian University of Technology,
No. 2 Linggong Road,
Dalian 116024, China
e-mail: yanliu@dlut.edu.cn

Min Zhang

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

Tianlong Zhang

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

Mengchao Zhang

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

Ying He

Key Laboratory of Ocean Energy Utilization and
Energy Conservation of Ministry of Education
Dalian University of Technology,
No. 2 Linggong Road,
Dalian 116024, China
e-mail: heying@dlut.edu.cn

1Corresponding author.

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received June 22, 2015; final manuscript received January 25, 2016; published online April 22, 2016. Assoc. Editor: Feng Liu.

J. Fluids Eng 138(7), 071103 (Apr 22, 2016) (8 pages) Paper No: FE-15-1421; doi: 10.1115/1.4032752 History: Received June 22, 2015; Revised January 25, 2016

This paper is a continuous study of a previously investigated novel winglet-shroud (WS) tip configuration. Two additional sealing fins are fixed on the WS tip to further reduce tip leakage. This configuration is referred to WS with seals (WSS) tip. Secondary flow structures and total pressure loss coefficients on a transverse plane downstream of the blade trailing edge are measured. Flow in a blade cascade is also numerically simulated to obtain more information of flow fields. Compared with the WS tip, both experimental and numerical results show that the WSS tip can further improve the aerodynamic performance as expected. Relative to the plain tip, the WSS and WS tips can reduce total pressure loss on one plane downstream of the blade trailing edge by 50% and 28%, respectively. This is mainly due to reduced intensity of tip leakage vortex (TLV). For the tip leakage mass flow rate, the WS tip decreases it by 33.6%, while the implement of two additional sealing fins contributes to an extremely high reduction of 88.7%. This demonstrates that the use of sealing fins is effective to control the tip leakage flow and improve flow fields. In addition, a deeper analysis by applying a normalized helicity scheme to identify the evolution of different vortices and by tracing trajectories of the fluid near the tip offers credible supports for results.

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Figures

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Fig. 1

Configurations of WS tips

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Fig. 2

Schematic of the cascade

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Fig. 3

Computational grid of the WS with sealing fins

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Fig. 4

Contours of Cpt and secondary flow patterns on the 1.36Cax plane for the plain tip case: (a) EXP. and (b) CFD

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Fig. 5

Cpt and Ytip value against the axial chord

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Fig. 6

Contours of Cpt and secondary flow patterns on the 1.36Cax plane: (a) WS-EXP., (b) WS-CFD, (c) WSS-EXP., and (d) WSS-CFD

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Fig. 7

A simple loss break down on the 1.36Cax plane

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Fig. 8

Predicted distributions of Cps on a limiting plane of the blade tip surfaces: (a) plain tip, (b) WS tip, and (c) WSS tip

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Fig. 9

Distributions of Cps on the blade surface at 97.5%h

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Fig. 10

Distributions of Cps on curves of projection of the WS profile at 97.5%h

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Fig. 11

Ytip value of the WS and WSS cases

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Fig. 12

The tip leakage mass flow rate

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Fig. 13

Vortex identification by depicting contours of Hn: (a) plain tip, (b) WS tip, and (c) WSS tip

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