0
Research Papers

Free-Stream Effects on the Cooling Performance of Cylindrical and Fan-Shaped Cooling Holes

[+] Author and Article Information
Christian Saumweber

 Institut für Angewandte Thermo- und Fluiddynamik, Hochschule Mannheim, Mannheim, 68163, Germanyc.saumweber@hs-mannheim.de

Achmed Schulz

 Institut für Thermische Strömungsmaschinen, Karlsruher Institut für Technologie, Karlsruhe, 76131, Germanyachmed.schulz@kit.edu

J. Turbomach 134(6), 061007 (Aug 27, 2012) (12 pages) doi:10.1115/1.4006287 History: Received March 14, 2011; Revised June 15, 2011; Published August 27, 2012; Online August 27, 2012

From literature and our own studies, it is known that the effects of hot gas cross-flow and, in particular, the turbulence of the hot gas flow highly influence the spreading of the coolant in the near hole vicinity. Moreover, the velocity of the hot gas flow expressed by a hot gas Mach number obviously plays a much more important role in the case of diffuser holes than with simple cylindrical holes. To realize a certain blowing rate, a higher pressure ratio needs to be established in the case of higher Mach numbers. This in turn may strongly affect the diffusion process in the expanded portion of a fan-shaped cooling hole. The said effects will be discussed in great detail. The effects of free-stream Mach number and free-stream turbulence, including turbulence intensity, integral length scale, and periodic unsteady wake flow will be considered. The comparative study is performed by means of discharge coefficients and by local and laterally averaged adiabatic film cooling effectiveness and heat transfer coefficients. Both cooling holes have a length-to-diameter ratio of 6 and an inclination angle of 30 deg. The fan-shaped hole has an expansion angle of 14 deg. The effect of the coolant cross-flow at the hole entrance is not considered in this study, i.e., plenum conditions exist at the hole entrance.

Copyright © 2012 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Geometry of film cooling holes

Grahic Jump Location
Figure 2

Local effectiveness of cylindrical and fan-shaped holes at low and high blowing rate (Mam  = 0.3, Mac  = 0.0, Tu = 2%)

Grahic Jump Location
Figure 3

Computed velocity field in the symmetry plane of a fan-shaped hole and the local effectiveness pattern on the cooled surface (top). Schematic representation of the according mechanisms (bottom). (M = 1.0, Mam  = 0.3, Mac  = 0.0, Tum  = 2%, adiabatic wall).

Grahic Jump Location
Figure 4

Laterally averaged film cooling effectiveness (left) and related heat transfer coefficients (right) of cylindrical and fan-shaped holes (Mam  = 0.3, Mac  = 0.0, Tu = 2%)

Grahic Jump Location
Figure 5

Laterally averaged and local film cooling effectiveness of cylindrical holes at various combinations of hot gas Mach number and blowing rate (Mac  = 0.0, Tu = 2%)

Grahic Jump Location
Figure 6

Local film cooling effectiveness of fan-shaped holes at various blowing rates and hot gas Mach numbers (Mac  = 0.0, Tu = 2%)

Grahic Jump Location
Figure 7

Laterally averaged effectiveness (left) and related heat transfer coefficients (right) of fan-shaped holes at varying combinations of blowing rate and hot gas Mach number (Mac  = 0.0, Tu = 2%)

Grahic Jump Location
Figure 8

Surface averaged effectiveness (left) and discharge coefficient (right) of fan-shaped holes versus pressure ratio (Mac  = 0.0, Tu = 2%)

Grahic Jump Location
Figure 9

Local film cooling effectiveness of cylindrical holes at varying free-stream turbulence intensity and low (top row) and high blowing rates (bottom row) (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 10

Local film cooling effectiveness of fan-shaped holes at varying free-stream turbulence intensity and low (top row) and high blowing rates (bottom row) (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 11

Laterally averaged effectiveness of cylindrical (left) and fan-shaped holes (right) at varying free-stream turbulence intensities (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 12

Calculated velocity field and gas temperature in a normal plane 3D downstream of a cylindrical hole (left) and a fan-shaped hole (right) (M = 1.0, Mam  = 0.3, Mac  = 0.0, Tum  = 5.2%, adiabatic wall)

Grahic Jump Location
Figure 13

Laterally averaged related heat transfer coefficients of cylindrical (left) and fan-shaped holes (right) at varying free-stream turbulence intensities (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 14

Discharge coefficients of cylindrical and fan-shaped holes at varying free-stream turbulence intensities (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 15

Effect of integral length scale on laterally averaged film cooling effectiveness of cylindrical (left) and fan-shaped holes (right) at constant free-stream turbulence intensity (Mam  = 0.3, Mac  = 0.0, Tu = 5.2%)

Grahic Jump Location
Figure 16

Local film cooling effectiveness of cylindrical holes at low (top row) and high (bottom row) blowing rates and varying wake frequencies (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 17

Local film cooling effectiveness of fan-shaped holes at low (top row) and high (bottom row) blowing rates and varying wake frequencies (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 18

Laterally averaged film cooling effectiveness of cylindrical (left) and fan-shaped holes (right) at varying free-stream turbulence intensity and wake frequencies (Mam  = 0.3, Mac  = 0.0)

Grahic Jump Location
Figure 19

Discharge coefficients of cylindrical and fan-shaped holes at varying wake frequencies (Mam  = 0.3, Mac  = 0.0)

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