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Research Papers

Comparison of Two-Dimensional and Three-Dimensional Turbine Airfoils in Combination With Nonaxisymmetric Endwall Contouring

[+] Author and Article Information
Tobias W. Zimmermann

Institute of Power Plant Technology,
Steam and Gas Turbines,
RWTH Aachen University,
Templergraben 55,
Aachen 52062, Germany
e-mail: zimmermann@ikdg.rwth-aachen.de

Oliver Curkovic

Institute of Power Plant Technology,
Steam and Gas Turbines,
RWTH Aachen University,
Templergraben 55,
Aachen 52062, Germany
e-mail: curkovic@ikdg.rwth-aachen.de

Manfred Wirsum

Institute of Power Plant Technology,
Steam and Gas Turbines,
RWTH Aachen University,
Templergraben 55,
Aachen 52062, Germany
e-mail: wirsum@ikdg.rwth-aachen.de

Andrew Fowler

General Electric Company,
Newbold Road,
Rugby CV21 2NH, UK
e-mail: andrew.fowler2@ge.com

Kush Patel

General Electric Company,
Newbold Road,
Rugby CV21 2NH, UK
e-mail: kush.patel@ge.com

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received July 1, 2016; final manuscript received November 4, 2016; published online February 7, 2017. Assoc. Editor: John Clark.

J. Turbomach 139(6), 061007 (Feb 07, 2017) (13 pages) Paper No: TURBO-16-1141; doi: 10.1115/1.4035274 History: Received July 01, 2016; Revised November 04, 2016

Tangential endwall contouring (TEWC) is intended to improve the turbomachinery blading efficiency. This paper summarizes the experimental and numerical investigation of a test turbine with endwall contoured vanes and blades. Constant section (2D) airfoils as well as optimized compound lean (3D) high pressure steam turbine blading in baseline and endwall contoured configurations have been examined. Brush seals (BSs) are implemented within the casing sided cavities to minimize the leakage flow near the tip endwalls, where the contouring is also applied. The pressure and temperature data that are recorded in three axial measuring planes are plotted to visualize the change in flow structure. This shows that the efficiency is increased for 2D airfoils by means of endwall contouring. However, the efficiency of the first stage suffers, and the endwall contouring is still beneficial for the overall performance of the engine. Both phenomena (an efficiency loss in stage one and an improvement of the performance in stage two) have also been measured for the optimized 3D configurations; thus, it can be expected that the endwall contouring has also a beneficial impact on the performance of multirow turbines. The numerical investigations demonstrate in detail, how the secondary flow phenomena are influenced by end-wall contouring and a description of the changes in vortex formations as well as blade loading are given for the various configurations. It has been found that for steady computational fluid dynamics (CFD) simulations the use of stage interfaces suppresses the positive effects of the endwall contour onto the downstream blade row.

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References

Figures

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Fig. 1

Two-stage axial air turbine test rig

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Fig. 2

Cross section of the two-stage axial turbine

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Fig. 3

Measures to prevent errors and to increase the quality of the measurement

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Fig. 4

Design attributes of endwall contouring [23]

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Fig. 5

Sealing configurations

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Fig. 6

Vane with bore holes to measure the pressure distribution along the surface

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Fig. 7

Operating point stability of the design point. Speed, inlet pressure, outlet pressure and inlet temperature plotted for a full measuring period of one OP.

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Fig. 8

Pressure drop within the cavity of R1 on casing side and resulting leakage flow for the design point

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Fig. 9

Total pressure distribution in MP12 and MP22 for all OPs

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Fig. 10

Distribution of flow angle alpha in MP12 and MP22 for all OPs referred to the inlet pressure

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Fig. 11

Contour plots of angle alpha in MP12 for all OPs and airfoil configurations (enlarged axis applicable to all plots)

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Fig. 12

Contour plots of velocity cm in MP12 for all OPs and airfoil configurations (enlarged axis applicable to all plots)

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Fig. 13

Efficiency of all configurations for all OPs referred to HPB2 BASE. Efficiency of both stages and turbine is calculated in Eq. (3). In addition, the turbine efficiency is calculated in Eq. (4).

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