Knowing the heat transfer coefficient augmentation is imperative to predicting film cooling performance on turbine components. In the past, heat transfer coefficient augmentation was generally measured at unit density ratio to keep measurements simple and uncertainty low. Some researchers have measured heat transfer coefficient augmentation while taking density ratio effects into account, but none have made direct temperature measurements of the wall and adiabatic wall to calculate hf/h0 at higher density ratios. This work presents results from measuring the heat transfer coefficient augmentation downstream of shaped holes with a 7 deg forward and lateral expansion at DR = 1.0, 1.2, and 1.5 on a flat plate using a constant heat flux surface. The results showed that the heat transfer coefficient augmentation was low while the jets were attached to the surface and increased when the jets started to separate. At DR = 1.0, hf/h0 was higher for a given blowing ratio than at DR = 1.2 and DR = 1.5. However, when velocity ratios are matched, better correspondence was found at the different density ratios. Surface contours of hf/h0 showed that the heat transfer was initially increased along the centerline of the jet, but was reduced along the centerline at distances farther downstream. The decrease along the centerline may be due to counter-rotating vortices sweeping warm air next to the heat flux plate toward the center of the jet, where they sweep upward and thicken the thermal boundary layer. This warming of the core of the coolant jet over the heated surface was confirmed with thermal field measurements.
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January 2017
Research-Article
Direct Measurement of Heat Transfer Coefficient Augmentation at Multiple Density Ratios
Emily J. Boyd,
Emily J. Boyd
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: emily.june.boyd@gmail.com
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: emily.june.boyd@gmail.com
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John W. McClintic,
John W. McClintic
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: jmcclintic@utexas.edu
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: jmcclintic@utexas.edu
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Kyle F. Chavez,
Kyle F. Chavez
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: kyle.f.chavez@utexas.edu
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: kyle.f.chavez@utexas.edu
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David G. Bogard
David G. Bogard
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: dbogard@mail.utexas.edu
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: dbogard@mail.utexas.edu
Search for other works by this author on:
Emily J. Boyd
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: emily.june.boyd@gmail.com
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: emily.june.boyd@gmail.com
John W. McClintic
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: jmcclintic@utexas.edu
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: jmcclintic@utexas.edu
Kyle F. Chavez
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: kyle.f.chavez@utexas.edu
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: kyle.f.chavez@utexas.edu
David G. Bogard
Department of Mechanical Engineering,
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: dbogard@mail.utexas.edu
The University of Texas at Austin,
204 E. Dean Keeton Street,
Austin, TX 78712
e-mail: dbogard@mail.utexas.edu
1Present address: Department of Mechanical Engineering & Materials Science, Washington University in St. Louis, St. Louis, MO 63130.
2Corresponding author.
3Present address: Williams International, Commerce Township, MI 48390.
Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received June 21, 2016; final manuscript received July 1, 2016; published online September 8, 2016. Editor: Kenneth Hall.
J. Turbomach. Jan 2017, 139(1): 011005 (11 pages)
Published Online: September 8, 2016
Article history
Received:
June 21, 2016
Revised:
July 1, 2016
Citation
Boyd, E. J., McClintic, J. W., Chavez, K. F., and Bogard, D. G. (September 8, 2016). "Direct Measurement of Heat Transfer Coefficient Augmentation at Multiple Density Ratios." ASME. J. Turbomach. January 2017; 139(1): 011005. https://doi.org/10.1115/1.4034190
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