0
Research Papers

Aerodynamic Optimization of a Winglet-Shroud Tip Geometry for a Linear Turbine Cascade

[+] Author and Article Information
Min Zhang

Key Laboratory of Ocean Energy Utilization and
Energy Conservation of Ministry of Education,
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

Yan Liu

Key Laboratory of Ocean Energy Utilization and
Energy Conservation of Ministry of Education,
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

Tianlong 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

Mengchao 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

Ying He

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

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received June 23, 2016; final manuscript received March 29, 2017; published online June 6, 2017. Editor: Kenneth Hall.

J. Turbomach 139(10), 101011 (Jun 06, 2017) (9 pages) Paper No: TURBO-16-1125; doi: 10.1115/1.4036647 History: Received June 23, 2016; Revised March 29, 2017

This paper presents a continued study on a previously investigated novel winglet-shroud (WS) (or partial shroud) geometry for a linear turbine cascade. Various widths of double-side winglets (DSW) and different locations of a partial shroud are considered. In addition, both a plain tip and a full shroud tip are applied as the datum cases which were examined experimentally and numerically. Total pressure loss and viscous loss coefficients are comparatively employed to execute a quantitative analysis of aerodynamic performance. The effectiveness of various widths (w) of DSW set at 3%, 5%, 7%, and 9% of the blade pitch (p) is numerically investigated. Skin-friction lines on the tip surface indicate that different DSW cases do not alter flow field features including the separation bubble and reattachment flow within the tip gap region, even for the case with the broadest width (w/p = 9%). However, the pressure side extension of the DSW exhibits the formation of separation bubble, while the suction side platform of the DSW turns the tip leakage vortex (TLV) away from the suction surface (SS). Meanwhile, the horse-shoe vortex (HV) near the casing is not generated even for the case with the smallest width (w/p = 3%). As a result, both the tip leakage and the upper passage vortices are weakened and further dissipated with wider w/p in the DSW cases. Larger width of the DSW geometry is indeed able to improve the aerodynamic performance, but only to a slight degree. With the w/p increasing from 3% to 9%, the mass-averaged total pressure loss coefficient over an exit plane is reduced by only 2.61%. Therefore, considering both the enlarged (or reduced) tip area and the enhanced (or deteriorated) performance compared to the datum cases, a favorable width of w/p = 5% is chosen to design the WS structure. Three locations for the partial shroud (linkage segment) are devised, locating them near the leading edge, in the middle and close to the trailing edge, respectively. Results demonstrate that all three cases of the WS design have advantages over the DSW arrangement in lessening the aerodynamic loss, with the middle linkage segment location producing the optimal effect. This conclusion verifies the feasibility of the previously studied WS configuration.

FIGURES IN THIS ARTICLE
<>
Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Denton, J. D. , 1993, “ The 1993 IGTI Scholar Lecture: Loss Mechanisms in Turbomachines,” ASME J. Turbomach., 115(4), pp. 621–656. [CrossRef]
Booth, T. C. , Dodge, P. R. , and Hepworth, H. K. , 1982, “ Rotor-Tip Leakage—Part I: Basic Methodology,” ASME J. Eng. Power, 104(1), pp. 154–161. [CrossRef]
Pfau, A. , Treiber, M. , Sell, M. , and Gyarmathy, G. , 2000, “ Flow Interaction From the Exit Cavity of an Axial Turbine Blade Row Labyrinth Seal,” ASME J. Turbomach., 123(2), pp. 342–352. [CrossRef]
EI-Dosoky, M. F. , Rona, A. , and Gostelow, J. P. , 2007, “ An Analytical Model for Over-Shroud Leakage Losses in a Shrouded Turbine Stage,” ASME Paper No. GT2007-27786.
Wallis, A. M. , Denton, J. D. , and Demargne, A. A. J. , 2000, “ The Control of Shroud Leakage Flows to Reduce Aerodynamic Losses in a Low Aspect Ratio, Shrouded Axial Flow Turbine,” ASME J. Turbomach., 123(2), pp. 334–341. [CrossRef]
Rosic, B. , and Denton, J. D. , 2008, “ Control of Shroud Leakage Loss by Reducing Circumferential Mixing,” ASME J. Turbomach., 130(2), p. 021010. [CrossRef]
Yoon, S. , Eric, C. , Denton, J. , and Longley, J. , 2013, “ The Effect of Clearance on Shrouded and Unshrouded Turbines at Two Levels of Reaction,” ASME J. Turbomach., 136(2), p. 021013. [CrossRef]
Bunker, R. S. , 2006, “ Axial Turbine Blade Tips: Function, Design, and Durability,” AIAA J. Propul. Power, 22(2), pp. 271–285. [CrossRef]
Porreca, L. , Behr, T. , Schlienger, J. , Kalfas, A. I. , Abhari, R. S. , Ehrhard, J. , and Janke, E. , 2005, “ Fluid Dynamics and Performance of Partially and Fully Shrouded Axial Turbines,” ASME J. Turbomach., 127(4), pp. 668–678. [CrossRef]
Porreca, L. , Kalfas, A. I. , and Abhari, R. S. , 2008, “ Optimized Shroud Design for Axial Turbine Aerodynamic Performance,” ASME J. Turbomach., 130(3), p. 031016. [CrossRef]
Nirmalan, N. V. , and Bailey, J. C. , 2005, “ Experimental Investigation of Aerodynamic Losses of Different Shapes of a Shrouded Blade Tip Section,” ASME Paper No. GT2005-68903.
Palmer, T. R. , Tan, C. S. , Montgomery, M. , Malandra, A. , Little, D. , Zuniga, H. , and Zhou, K. Y. , 2015, “ Effects of Shroud Asymmetry on the Turbine Tip Shroud Cavity Flow Field,” ASME Paper No. GT2015-43721.
Mamaev, B. I. , Petukhovsky, M. M. , and Pozdnyakov, A. V. , 2013, “ Shrouding the First Blade of High Temperature Turbines,” ASME Paper No. TBTS2013-2001.
Shavalikul, A. , and Camci, C. , 2008, “ A Comparative Analysis of Pressure Sides Extension for Tip Leakage Control in Axial Turbines,” ASME Paper No. GT2008-50782.
Lee, S. W. , Kim, S. U. , and Kim, K. H. , 2012, “ Aerodynamic Performance of Winglets Covering the Tip Gap Inlet in a Turbine Cascade,” Int. J. Heat Fluid Flow, 34, pp. 36–46. [CrossRef]
Seo, Y. C. , and Lee, S. W. , 2013, “ Tip Gap Flow and Aerodynamic Loss Generation in a Turbine Cascade Equipped With Suction-Side Winglets,” J. Mech. Sci. Technol., 27(3), pp. 703–712. [CrossRef]
Zhou, C. , Hodson, H. , Tibbott, I. , and Stokes, M. , 2013, “ Effects of Winglet Geometry on the Aerodynamic Performance of Tip Leakage Flow in a Turbine Cascade,” ASME J. Turbomach., 135(5), p. 051009. [CrossRef]
Dey, D. , and Camci, C. , 2001, “ Aerodynamic Tip Desensitization of an Axial Turbine Rotor Using Tip Platform Extensions,” ASME Paper No. 2001-GT-0484.
Schabowski, Z. , and Hodson, H. , 2013, “ The Reduction of Over Tip Leakage Loss in Unshrouded Axial Turbines Using Winglets and Squealers,” ASME J. Turbomach., 136(4), p. 041001. [CrossRef]
Coull, J. D. , Atkins, N. R. , and Hodson, H. P. , 2014, “ Winglets for Improved Aerothermal Performance of High Pressure Turbines,” ASME J. Turbomach., 136(9), p. 091007. [CrossRef]
Liu, Y. , Zhang, T. L. , Zhang, M. , and Zhang, M. C. , 2015, “ Numerical and Experimental Investigation of Aerodynamic Performance for a Straight Turbine Cascade With a Novel Partial Shroud,” ASME J. Fluids Eng., 138(3), p. 031206. [CrossRef]
Behr, T. , 2007, “ Control of Rotor Tip Leakage and Secondary Flow by Casing Air Injection in Unshrouded Axial Turbine,” Ph.D. thesis, Swiss Federal Institute of Technology, Zurich, Switzerland.
Zlatinov, M. B. , Tan, C. S. , Montgomery, M. , Islam, T. , and Harris, M. , 2012, “ Turbine Hub and Shroud Sealing Flow Loss Mechanisms,” ASME J. Turbomach., 134(6), p. 061027. [CrossRef]
Pullan, G. , Denton, J. , and Curtis, E. , 2004, “ Improving the Performance of a Turbine With Low Aspect Ratio Stators by Aft-Loading,” ASME J. Turbomach., 128(3), pp. 492–499. [CrossRef]
Denton, J. D. , and Pullan, G. , 2012, “ A Numerical Investigation Into the Sources of Endwall Loss in Axial Flow Turbines,” ASME Paper No. GT2012-69173.
Harrison, S. , 1990, “ Secondary Loss Generation in a Linear Cascade of High-Turning Turbine Blades,” ASME J. Turbomach., 112(4), pp. 618–624. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Design process of the winglet-shroud geometry

Grahic Jump Location
Fig. 3

Experimental cascade

Grahic Jump Location
Fig. 4

Computational domain

Grahic Jump Location
Fig. 5

Distribution of Cpt and secondary flow streamlines: (a) in case 1, CFD, (b) in case 2, CFD, and (c) on the upper span area of 1.36Cax plane, EXP

Grahic Jump Location
Fig. 6

Axial distributions of Cpt and wvis for cases 1 and 2

Grahic Jump Location
Fig. 7

Loss breakdown for cases 1–6

Grahic Jump Location
Fig. 8

Contours of Sv on the upper half span area of 1.36Cax plane: (a) case 3, (b) case 4, (c) case 5, and (d) case 6

Grahic Jump Location
Fig. 9

Contours of Cps on the tip surfaces for cases 1–6 and axial distributions of Cps on the blade surface at 97.5%h for cases 1 and 3–6

Grahic Jump Location
Fig. 10

Flow features on the casing: (a) case 1 and (b) case 6

Grahic Jump Location
Fig. 11

Flow features on various axial planes: (a) case 7, (b) case 8, and (c) case 9

Grahic Jump Location
Fig. 12

Axial distributions of Cps and loss breakdown for cases 7–9

Grahic Jump Location
Fig. 13

Predicted tip leakage mass flow rates for cases 1, 4, and 7–9

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In