0
Research Papers

Measurements of Adiabatic Film and Overall Cooling Effectiveness on a Turbine Vane Pressure Side With a Trench

[+] Author and Article Information
David G. Bogard

Department of Mechanical Engineering,
The University of Texas at Austin,
Austin, TX 78712

1Present address: GE Energy, Greenville, SC.

Contributed by the International Gas Turbine Institute (IGTI) of ASME for publication in the JOURNAL OF TURBOMACHINERY. Manuscript received April 28, 2012; final manuscript received September 30, 2012; published online June 26, 2013. Editor: David Wisler.

J. Turbomach 135(5), 051007 (Jun 26, 2013) (11 pages) Paper No: TURBO-12-1035; doi: 10.1115/1.4007820 History: Received April 28, 2012; Revised September 30, 2012

Film cooling performance is typically quantified by separating the external convective heat transfer from the other components of the conjugate heat transfer that occurs in turbine airfoils. However, it is also valuable to assess the conjugate heat transfer in terms of the overall cooling effectiveness, which is a parameter of importance to airfoil designers. In the current study, adiabatic film effectiveness and overall cooling effectiveness values were measured for the pressure side of a simplified turbine vane model with three rows of showerhead cooling at the leading edge and one row of body film cooling holes on the pressure side. This was done by utilizing two geometrically identical models made from different materials. Adiabatic film effectiveness was measured using a very low thermal conductivity material, and the overall cooling effectiveness was measured using a material with a higher thermal conductivity selected such that the Biot number of the model matched that of a turbine vane at engine conditions. The theoretical basis for this matched-Biot number modeling technique is discussed in some detail. Additionally, two designs of pressure side body film cooling holes were considered in this study: a standard design of straight, cylindrical holes and an advanced design of “trenched” cooling holes in which the hole exits were situated in a recessed, transverse trench. This study was performed using engine representative flow conditions, including a coolant-to-mainstream density ratio of DR = 1.4 and a mainstream turbulence intensity of Tu = 20%. The results of this study show that adiabatic film and overall cooling effectiveness increase with blowing ratio for the showerhead and pressure side trenched holes. Performance decreases with blowing ratio for the standard holes due to coolant jet separation from the surface. Both body film designs have similar performance at a lower blowing ratio when the standard hole coolant jets remain attached. Far downstream of the cooling holes both designs perform similarly because film effectiveness decays more rapidly for the trenched holes.

Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Error in ϕ caused by kf/kc discrepancy in matched-Bi technique, for Bi = 0.5 and (hf/hc)engine = 0.5

Grahic Jump Location
Fig. 5

PS film row trenched cooling hole schematic

Grahic Jump Location
Fig. 3

Coolant piping schematic

Grahic Jump Location
Fig. 4

Vane model cross section schematic with hatch locations shown

Grahic Jump Location
Fig. 7

Comparison of adiabatic film effectiveness (η) for trenched PS holes to data from Dorrington et al. [10]

Grahic Jump Location
Fig. 11

Showerhead + trenched PS holes adiabatic film effectiveness (η) contours for low and high blowing ratios

Grahic Jump Location
Fig. 8

Showerhead + standard PS holes laterally averaged adiabatic film effectiveness (η) for varying blowing ratios

Grahic Jump Location
Fig. 9

Showerhead + trenched PS holes laterally averaged adiabatic film effectiveness (η) for varying blowing ratios

Grahic Jump Location
Fig. 10

Showerhead + standard PS holes adiabatic film effectiveness (η) contours for low and high blowing ratios

Grahic Jump Location
Fig. 6

Comparison of adiabatic film effectiveness (η) for standard PS holes to data from Ames [12]

Grahic Jump Location
Fig. 12

Showerhead + standard PS holes laterally averaged overall cooling effectiveness (ϕ) for varying blowing ratios

Grahic Jump Location
Fig. 13

Showerhead + trenched PS holes laterally averaged overall cooling effectiveness (ϕ) for varying blowing ratios

Grahic Jump Location
Fig. 14

Showerhead + standard PS holes overall cooling effectiveness (ϕ) contours for low and high blowing ratios

Grahic Jump Location
Fig. 15

Showerhead + trenched PS holes overall cooling effectiveness (ϕ) contours for low and high blowing ratios

Grahic Jump Location
Fig. 2

Wind tunnel and test section schematics

Grahic Jump Location
Fig. 16

Comparison of standard and trenched holes laterally averaged η and ϕ for lowest blowing ratio (MPS = 1.0)

Grahic Jump Location
Fig. 17

Comparison of standard and trenched holes laterally averaged η and ϕ for highest blowing ratio (MPS = 2.9–3.0)

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