Pulsed film cooling was studied experimentally to determine its effect on film-cooling effectiveness and heat transfer. The film-cooling jets were pulsed using solenoid valves in the supply air line. Cases with a single row of cylindrical film-cooling holes inclined at 35 deg to the surface of a flat plate were considered at blowing ratios of 0.25, 0.5, 1.0, and 1.5 for a variety of pulsing frequencies and duty cycles. Temperature measurements were made using an infrared camera and thermocouples. The plate was equipped with constant flux surface heaters, and data were acquired for each flow condition with the plate both heated and unheated. The local film-cooling effectiveness, Stanton numbers, and heat flux ratios were calculated and compared to baseline cases with continuous blowing and no blowing. Stanton number signatures on the surface provided evidence of flow structures, including horseshoe vortices wrapping around the film-cooling jets and vortices within the jets. Pulsing tends to increase Stanton numbers, and the effect tends to increase with pulsing frequency and duty cycle. Some exceptions were observed, however, at the highest frequencies tested. Overall heat flux ratios also show that pulsing tends to have a detrimental effect with some exceptions at the highest frequencies. The best overall film cooling was achieved with continuous jets and a blowing ratio of 0.5. The present results may prove useful for understanding film-cooling behavior in engines, where mainflow unsteadiness causes film-cooling jet pulsation.
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e-mail: volino@usna.edu
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April 2007
Technical Papers
Effect of Jet Pulsing on Film Cooling—Part II: Heat Transfer Results
Sarah M. Coulthard,
Sarah M. Coulthard
Department of Mechanical Engineering,
Stanford University
, Stanford, CA 94305
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Ralph J. Volino,
Ralph J. Volino
Department of Mechanical Engineering,
e-mail: volino@usna.edu
United States Naval Academy
, Annapolis, MD 21402
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Karen A. Flack
Karen A. Flack
Department of Mechanical Engineering,
United States Naval Academy
, Annapolis, MD 21402
Search for other works by this author on:
Sarah M. Coulthard
Department of Mechanical Engineering,
Stanford University
, Stanford, CA 94305
Ralph J. Volino
Department of Mechanical Engineering,
United States Naval Academy
, Annapolis, MD 21402e-mail: volino@usna.edu
Karen A. Flack
Department of Mechanical Engineering,
United States Naval Academy
, Annapolis, MD 21402J. Turbomach. Apr 2007, 129(2): 247-257 (11 pages)
Published Online: May 31, 2006
Article history
Received:
May 24, 2006
Revised:
May 31, 2006
Connected Content
A correction has been published:
Effect of Jet Pulsing on Film Cooling—Part I: Effectiveness and Flow-Field Temperature Results
Citation
Coulthard, S. M., Volino, R. J., and Flack, K. A. (May 31, 2006). "Effect of Jet Pulsing on Film Cooling—Part II: Heat Transfer Results." ASME. J. Turbomach. April 2007; 129(2): 247–257. https://doi.org/10.1115/1.2437230
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