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Heat and Mass Transfer

, Volume 44, Issue 8, pp 989–998 | Cite as

Film cooling effectiveness from trenched shaped and compound holes

  • S. BaheriEmail author
  • S. P. Alavi Tabrizi
  • B. A. Jubran
Original

Abstract

This paper presents a comparative-numerical investigation on film cooling from a row of simple and compound-angle holes injected at 35° on a flat plate with four film cooling configurations: (1) cylindrical film hole; (2) 15° forward diffused film hole; (3) trenched cylindrical film hole; (4) trenched 15° forward-diffused film hole. All simulations are at fixed density ratio of 1.6, blowing ratio of 1.25, length-to-diameter L/D = 4 and pitch-to-diameter ratio of 3.0. The effect of length-to-diameter ratio on film cooling has been also investigated using L/D in the range of 1–8. Computational solutions of the steady, Reynolds-averaged Navier–Stokes equations have been obtained using a finite volume method. It has been found that the shape of the hole and the trenched holes can significantly affect the film cooling flow over the protected surface. Further, it has been shown that the film cooling effectiveness by trenched shaped holes is higher than all other configurations both in spanwise and streamwise specially downstream of the injection. Also, a trenched compound angle injection shaped hole produces much higher film cooling protection than the other configurations investigated in the present paper. The length-to-diameter ratio of trenched holes was found to have a significant effect on film cooling effectiveness and the spread of the coolant jets.

Keywords

Trench Vortex Pair Film Cool Cylindrical Hole Shaped Hole 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols

D

diameter of film-hole

k

turbulent kinetic energy

L/D

length-to-diameter ratio of film hole

M

blowing ratio = \( (\rho U)_{c} /(\rho U)_{\infty } \)

P/D

pitch-to-diameter ratio of film hole

Re

Reynolds number

T

local fluid temperature

Tu

turbulence intensity

u*

friction velocity; \( u_{ * } = {\sqrt {\tau _{w} /\rho } } \)

W/D

slot width to hole diameter ratio

X

coordinate in the streamwise direction

Y

coordinate normal to the test surface

y+

the normalized distance; \( y^{ + } = \frac{{yu_{ * } }} {\nu } \)

Z

coordinate in the lateral direction

Greek symbols

β

streamwise injection angle

ε

dissipation rate of turbulent kinetic energy

Φ

Lateral injection angle

η (eta)

adiabatic film effectiveness; \( \eta = \frac{{T - T_{\infty } }} {{T_{c} - T_{\infty } }} \)

ρ

density of the fluid

τw

wall shear stress

Subscripts

c

coolant

w

wall

free stream

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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • S. Baheri
    • 1
    Email author
  • S. P. Alavi Tabrizi
    • 1
  • B. A. Jubran
    • 2
  1. 1.Faculty of Mechanical EngineeringTabriz UniversityTabrizIran
  2. 2.Department of Aerospace EngineeringRyerson University, AIAA MemberTorontoCanada

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