0
TECHNICAL PAPERS

Effect of Jet Pulsing on Film Cooling—Part II: Heat Transfer Results

[+] Author and Article Information
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 21402volino@usna.edu

Karen A. Flack

Department of Mechanical Engineering, United States Naval Academy, Annapolis, MD 21402

J. Turbomach 129(2), 247-257 (May 31, 2006) (11 pages) doi:10.1115/1.2437230 History: Received May 24, 2006; Revised May 31, 2006

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.

Copyright © 2007 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 8

Stf∕Sto contours at various pulsing frequencies with nominal B=1.0, DC=0.5

Grahic Jump Location
Figure 9

Stf∕Sto for nominal B=1.0, DC=0.5 and steady B=0.5 and B=0.25 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 10

qf∕qo for nominal B=1.0, DC=0.5 and steady B=0.5 and B=0.25 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 11

Stf∕Sto contours at various duty cycles with nominal B=0.5 and F=0.0238

Grahic Jump Location
Figure 12

Stf∕Sto for nominal B=0.5, F=0.0238 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 13

qf∕qo for nominal B=0.5, F=0.0238 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 14

Stf∕Sto contours at various duty cycles with nominal B=1.0 and F=0.0238

Grahic Jump Location
Figure 15

Stf∕Sto for nominal B=1.0, F=0.0238 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 16

qf∕qo for nominal B=1.0, F=0.0238 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 17

Film-cooling effectiveness contours at various duty cycles with nominal B=1.0 and F=0.1905

Grahic Jump Location
Figure 18

Stf∕Sto for nominal B=1.0 and F=0.1905 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 19

qf∕qo for nominal B=1.0 and F=0.1905 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 7

qf∕qo for nominal B=0.5, DC=0.5 and steady B=0.5 and B=0.25 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 6

Stf∕Sto for nominal B=0.5, DC=0.5 and steady B=0.5 and B=0.25 cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 5

Stf∕Sto contours at various pulsing frequencies with nominal B=0.5 and DC=0.5

Grahic Jump Location
Figure 4

qf∕qo for steady blowing cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 3

Stf∕Sto for steady blowing cases: (a) centerline and (b) spanwise averaged

Grahic Jump Location
Figure 2

Stf∕Sto contours for steady blowing with B=0.25, 0.5, 1.0, and 1.5

Grahic Jump Location
Figure 1

Spanwise averaged Stanton number with no blowing, Sto

Tables

Errata

Discussions

Related

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