0
Research Papers

Film Cooling Effectiveness Improvements Using a Nondiffusing Oval Hole

[+] Author and Article Information
Emin Issakhanian

Department of Mechanical Engineering,
Loyola Marymount University,
Los Angeles, CA 90045
e-mail: emin.issakhanian@lmu.edu

Christopher J. Elkins, John K. Eaton

Department of Mechanical Engineering,
Stanford University,
Stanford, CA 94305

1Corresponding author.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received October 17, 2015; final manuscript received November 5, 2015; published online December 29, 2015. Editor: Kenneth C. Hall.

J. Turbomach 138(4), 041004 (Dec 29, 2015) (6 pages) Paper No: TURBO-15-1229; doi: 10.1115/1.4032045 History: Received October 17, 2015; Revised November 05, 2015

The need for improvements in film cooling effectiveness over traditional cylindrical film cooling holes has led to varied shaped hole and sister hole designs of increasing complexity. This paper presents a simpler shaped hole design which shows improved film cooling effectiveness over both cylindrical holes and diffusing fan-shaped holes without the geometric complexity of the latter. Magnetic resonance imaging measurement techniques are used to reveal the coupled 3D velocity and coolant mixing from film cooling holes which are of a constant oval cross section as opposed to round. The oval-shaped hole yielded an area-averaged adiabatic effectiveness twice that of the diffusing fan-shaped hole tested. Three component mean velocity measurements within the channel and cooling hole showed the flow features and vorticity fields which explain the improved performance of the oval-shaped hole. As compared to the round hole, the oval hole leads to a more complex vorticity field, which reduces the strength of the main counter-rotating vortex pair (CVP). The CVP acts to lift the coolant away from the turbine blade surface, and thus strongly reduces the film cooling effectiveness. The weaker vortices allow the coolant to stay closer to the blade surface and to remain relatively unmixed with the main flow over a longer distance. Thus, the oval-shaped film cooling hole provides a simpler solution for improving film cooling effectiveness beyond circular hole and diffusing hole designs.

Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Goldstein, R. J. , Eckert, E. R. G. , and Burggraf, F. , 1974, “ Effects of Hole Geometry and Density on Three-Dimensional Film Cooling,” Int. J. Heat Mass Transfer, 17(5), pp. 595–607. [CrossRef]
Thole, K. , Gritsch, M. , Schulz, A. , and Wittig, S. , 1996, “ Flowfield Measurements for Film Cooling Holes With Expanded Exits,” ASME Paper No. 96-GT-174.
Ganzert, W. , Hildebrandt, T. , and Fottner, L. , 2000, “ Systematic Experimental and Numerical Investigations on the Aerothermodynamics of a Film Cooled Turbine Cascade With Variation of the Cooling Hole Shape: Part I—Experimental Approach,” ASME Paper No. 2000-GT-0295.
Heidmann, J. D. , and Ekkad, S. V. , 2008, “ A Novel Antivortex Turbine Film-Cooling Hole Concept,” ASME J. Turbomach., 130(3), p. 031020. [CrossRef]
Okita, Y. , and Nishiura, M. , 2007, “ Film Effectiveness Performance of an Arrowhead-Shaped Film-Cooling Hole Geometry,” ASME J. Turbomach., 129(2), pp. 331–339. [CrossRef]
Kusterer, K. , Elyas, A. , Bohn, D. , Sugimoto, T. , Tanaka, R. , and Kazari, M. , 2011, “ The NEKOMIMI Cooling Technology: Cooling Holes With Ears for High-Efficient Film Cooling,” ASME Paper No. GT2011-45524.
Haven, B. A. , and Kurosaka, M. , 1997, “ Kidney and Anti-Kidney Vortices in Crossflow Jets,” J. Fluid Mech., 352, pp. 27–64. [CrossRef]
Issakhanian, E. , Elkins, C. J. , and Eaton, J. K. , 2012, “ In-Hole and Mainflow Velocity Measurements of Low-Momentum Jets in Crossflow Emanating From Short Holes,” Exp. Fluids, 53(6), pp. 1765–1778. [CrossRef]
Issakhanian, E. , Elkins, C. J. , and Eaton, J. K. , 2012, “ Magnetic Resonance Imaging Studies of Flow and Mixing for Single-Hole Film Cooling,” ASME Paper No. GT2011-45134.
Elkins, C. , and Alley, M. , 2007, “ Magnetic Resonance Velocimetry: Applications of Magnetic Resonance Imaging in the Measurement of Fluid Motion,” Exp. Fluids, 43(6), pp. 823–858. [CrossRef]
Issakhanian, E. , 2012, “ 3D Velocity and Scalar Field Measurements of Discrete Hole Film Cooling Flows,” Ph.D. dissertation, Stanford University, Stanford, CA.
Schroeder, R. P. , and Thole, K. , 2014, “ Adiabatic Effectiveness Measurements for a Baseline Shaped Film Cooling Hole,” ASME Paper No. GT2014-25992.

Figures

Grahic Jump Location
Fig. 1

Cross-sectional view of tunnel contraction, development section, test section, feed plenum, hole insert, and outlet. All dimensions are in mm.

Grahic Jump Location
Fig. 2

Schematic side view of plenum, hole, and test section. Gray area denotes MRV measurement volume.

Grahic Jump Location
Fig. 3

Schematic of tested hole shapes: oval- (top) and fan-shaped (bottom). Dimensions are in mm unless otherwise stated.

Grahic Jump Location
Fig. 4

Adiabatic surface effectiveness, η, map for the oval-shaped hole. Plot values have been filtered.

Grahic Jump Location
Fig. 5

Adiabatic surface effectiveness, η, map for the fan-shaped hole. Plot values have been filtered.

Grahic Jump Location
Fig. 6

Laterally averaged adiabatic surface effectiveness, η¯, versus streamwise position for the oval-shaped hole (top) and the fan-shaped hole (bottom). Plot values have been filtered.

Grahic Jump Location
Fig. 7

Ratio of laterally averaged adiabatic surface effectiveness, η¯, of the oval-shaped hole to that of the fan-shaped hole plotted against streamwise position

Grahic Jump Location
Fig. 8

Isostreamwise vorticity surfaces at threshold levels of 0.5 (bottom) and −0.5 (top) for oval-shaped hole

Grahic Jump Location
Fig. 9

Midhole secondary flow velocity vectors for oval-shaped hole

Grahic Jump Location
Fig. 10

Contours of streamwise vorticity and in-plane velocity vectors at x/D = 4 for fan-shaped hole

Grahic Jump Location
Fig. 11

Contours of streamwise vorticity and in-plane velocity vectors at x/D = 4 for oval-shaped hole

Grahic Jump Location
Fig. 12

Contours of normalized streamwise velocity overlaid with in-plane velocity vectors and lines of isonormalized temperature for the fan-shaped hole

Grahic Jump Location
Fig. 13

Contours of normalized streamwise velocity overlaid with in-plane velocity vectors and lines of isonormalized temperature for the oval-shaped hole

Grahic Jump Location
Fig. 14

Contours of normalized temperature in the symmetry plane for the fan-shaped hole. Streamlines originating at windward and leeward edges of hole overlaid.

Grahic Jump Location
Fig. 15

Contours of normalized temperature in the symmetry plane for the oval-shaped hole. Streamlines originating at windward and leeward edges of hole overlaid.

Grahic Jump Location
Fig. 16

θ = 0.25 isosurfaces for the fan-shaped hole (green) and oval hole (orange), see online version for color

Grahic Jump Location
Fig. 17

Contours of velocity ratio magnitude at oval hole exit plane

Grahic Jump Location
Fig. 18

Revised cooling hole feed plenum. Nonessential geometry is suppressed for clarity. Dimensions are in mm unless otherwise stated.

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