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.
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April 2016
Research-Article
Film Cooling Effectiveness Improvements Using a Nondiffusing Oval Hole
Emin Issakhanian,
Emin Issakhanian
Department of Mechanical Engineering,
Loyola Marymount University,
Los Angeles, CA 90045
e-mail: emin.issakhanian@lmu.edu
Loyola Marymount University,
Los Angeles, CA 90045
e-mail: emin.issakhanian@lmu.edu
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Christopher J. Elkins,
Christopher J. Elkins
Department of Mechanical Engineering,
Stanford University,
Stanford, CA 94305
Stanford University,
Stanford, CA 94305
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John K. Eaton
John K. Eaton
Department of Mechanical Engineering,
Stanford University,
Stanford, CA 94305
Stanford University,
Stanford, CA 94305
Search for other works by this author on:
Emin Issakhanian
Department of Mechanical Engineering,
Loyola Marymount University,
Los Angeles, CA 90045
e-mail: emin.issakhanian@lmu.edu
Loyola Marymount University,
Los Angeles, CA 90045
e-mail: emin.issakhanian@lmu.edu
Christopher J. Elkins
Department of Mechanical Engineering,
Stanford University,
Stanford, CA 94305
Stanford University,
Stanford, CA 94305
John K. Eaton
Department of Mechanical Engineering,
Stanford University,
Stanford, CA 94305
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. Apr 2016, 138(4): 041004 (6 pages)
Published Online: December 29, 2015
Article history
Received:
October 17, 2015
Revised:
November 5, 2015
Citation
Issakhanian, E., Elkins, C. J., and Eaton, J. K. (December 29, 2015). "Film Cooling Effectiveness Improvements Using a Nondiffusing Oval Hole." ASME. J. Turbomach. April 2016; 138(4): 041004. https://doi.org/10.1115/1.4032045
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