Research Papers

Effect of Endwall Contouring on a Transonic Turbine Blade Passage: Heat Transfer Performance

[+] Author and Article Information
Kapil V. Panchal

Elliott Group,
901 North Fourth Street,
Jeannette, PA 15644
e-mail: kpanchal@elliott-turbo.com

Santosh Abraham

Siemens Energy, Inc.,
5101 Westinghouse Boulevard,
Charlotte, NC 28273-9640
e-mail: santosh.abraham@siemens.com

Arnab Roy

Department of Mechanical Engineering,
Virginia Tech,
Blacksburg, VA 24061
e-mail: arnab8@vt.edu

Srinath V. Ekkad

Department of Mechanical Engineering,
301 Burruss Hall,
800 Drillfield Drive,
Blacksburg, VA 24061
e-mail: sekkad@vt.edu

Wing Ng

Department of Mechanical Engineering,
Virginia Tech,
425 Goodwin Hall (0238),
635 Prices Fork Road,
Blacksburg, VA 24061
e-mail: wng@vt.edu

Andrew S. Lohaus

Siemens Energy, Inc.,
4400 Alafaya Trail,
Orlando, FL 32789
e-mail: andrew.lohaus@siemens.com

Michael E. Crawford

Siemens Energy, Inc.,
11842 Corporate Boulevard,
Orlando, FL 32817
e-mail: michaelcrawford@siemens.com

1Corresponding author.

2Present address: National Energy Technology Laboratory, Morgantown, WV 26507.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received March 4, 2016; final manuscript received July 22, 2016; published online September 20, 2016. Assoc. Editor: Jim Downs.

J. Turbomach 139(1), 011009 (Sep 20, 2016) (11 pages) Paper No: TURBO-16-1061; doi: 10.1115/1.4034411 History: Received March 04, 2016; Revised July 22, 2016

Effect of turbine endwall contouring on its aerodynamic performance has been widely studied, but only a few studies are available in the open literature investigating its effect on heat transfer performance; especially at transonic exit Mach number conditions. In this paper, we report a study of effect of contouring on endwall heat transfer performance of a high-turning high-pressure (HP) turbine blade passage operating under transonic exit conditions. The paper describes comparison of heat transfer performance of two contoured endwall geometries, one aerodynamically optimized (AO) and the other heat transfer optimized (HTO), with a baseline, noncontoured geometry. The endwall geometries were experimentally investigated at Virginia Tech's transient, blow down, transonic linear cascade facility at three exit Mach numbers, Mex= 0.71, 0.88(design) and 0.95, for their heat transfer performance. Endwall surface temperatures were measured using infrared (IR) thermography and local heat transfer coefficient (HTC) values were calculated using measured temperatures. A camera matrix model-based data postprocessing technique was developed to relate the two-dimensional images captured by IR camera to three-dimensional endwall contours. The measurement technique and the methodology for postprocessing of the heat transfer coefficient data have been presented in detail. Discussion and interpretation of experimental results have been augmented using aerodynamic CFD simulations of the geometries. Both the contoured endwalls demonstrated a significant reduction in the overall average heat transfer coefficient values of the order of 10%. The surface Stanton number distributions also indicated a reduction in the level of hot spots for most of the endwall surface. However, at some locations an increase was also observed, especially in the area near the leading edge (LE). The results indicate that the endwall contouring could significantly improve heat transfer performance of turbine passages.

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Fig. 1

Endwall geometries: (a) baseline noncontoured endwall, (b) aero-optimized endwall, and (c) heat transfer optimized endwall

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Fig. 2

Schematic view of Virginia Tech transonic cascade tunnel facility

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Fig. 3

Cascade test section

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Fig. 4

Temperature measurement setup

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Fig. 5

Tunnel temperature history and data processing window

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Fig. 6

Linear regression plot for uncooled heat transfer

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Fig. 7

Wall Temperature change history during an experimental run

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Fig. 8

(a) The experimental setup with IR window, (b) examples of camera orientations for the data acquisition through the top and the bottom windows, and (c) sample plots of HTC data for the top and the bottom windows

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Fig. 9

HTC data extraction and postprocessing steps: (a) HTC plots, (b) find camera matrix, (c) extract HTC data on the endwall, (d) plot of HTC data for the baseline endwall for a single window, and (e) combine top and bottom window data and remove the data at junction

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Fig. 10

Stanton number distribution for baseline geometry

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Fig. 11

Effect of endwall contouring on St values, Mex = 0.88 : (a) baseline, (b) AO, and (c) HTO

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Fig. 12

Near endwall velocity distribution at Mex = 0.88: (a) baseline, (b) AO, and (c) HTC

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Fig. 13

Endwall Stanton number change with respect to time baseline at Mex = 0.88: (a) AO and (b) HTO

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Fig. 14

Stanton number plots for baseline geometry: (a) Mex = 0.71, (b) Mex = 0.88, and (c) Mex = 0.95




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