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Research Papers: Fundamental Issues and Canonical Flows

Compound Triple Jets Film Cooling Improvements via Velocity and Density Ratios: Large Eddy Simulation

[+] Author and Article Information
R. Farhadi-Azar, M. Taeibi-Rahni, M. Salimi

Department of Aerospace Engineering, Sharif University of Technology, Tehran, Iran, 1384674334

M. Ramezanizadeh1

Department of Aerospace Engineering, Shahid Sattari Air University, Tehran, Iran, 1384674334ramezanizadeh@mech.sharif.ir

1

Corresponding author.

J. Fluids Eng 133(3), 031202 (Mar 10, 2011) (13 pages) doi:10.1115/1.4003589 History: Received January 19, 2010; Revised February 03, 2011; Published March 10, 2011; Online March 10, 2011

The flow hydrodynamic effects and film cooling effectiveness placing two small coolant ports just upstream the main jet (combined triple jets) were numerically investigated. Cross sections of all jets are rectangular and they are inclined normally into the hot cross-flow. The finite volume method and the SIMPLE algorithm on a multiblock nonuniform staggered grid were applied. The large-eddy simulation approach with three different subgrid scale models was used. The obtained results showed that this flow configuration reduces the mixing between the freestream and the coolant jets and hence provides considerable improvements in film cooling effectiveness (both centerline and spanwise averaged effectiveness). Moreover, the effects of density and velocity differences between the jets and cross-flow and between each of the jets were investigated. The related results showed that any increase in density ratio will increase the penetration of the jet into the cross-flow, but increasing the density ratio also increases the centerline and spanwise average film cooling effectiveness. Increasing the smaller jet velocity ratios, compared with the main jet, significantly improve the cooling effectiveness and uniform coolant distribution over the surface by keeping the main jet coolant fluid very close to the wall.

Copyright © 2011 by American Society of Mechanical Engineers
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Figures

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Figure 1

Grid resolution study using time averaged U-velocity profiles at X/D=5 and time averaged kinetic energy profiles at X/D=3 for Z/D=0.0

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Figure 2

Schematic of the applied grid in the x-y and x-z planes

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Figure 3

Schematic of the computational domain for the CTJ structure

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Figure 4

(a) Comparison of the time averaged U-velocity profiles at X/D=0.0,1.0. (b) Comparison of the time averaged U-velocity profiles at X/D=3.0,5.0.

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Figure 5

Comparison of the time averaged W-velocity profiles at X/D=1.0,3.0

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Figure 6

Comparison of the time averaged V-velocity profiles at X/D=1.0,3.0

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Figure 7

The streamlines of the lateral-spanwise velocity components at X/D=3.0: (a) single jet and (b) CTJ structure

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Figure 8

The streamlines of the lateral-spanwise velocity components at X/D=3.0

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Figure 9

The streamlines of the streamwise-spanwise velocity components at Y/D=0.1: (a) single jet and (b) CTJ structure

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Figure 10

Temperature contours at Y/D=0.1: (a) single jet and (b) CTJ structure

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Figure 11

Temperature contours at X/D=3.0: (a) single jet and (b) CTJ structure

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Figure 12

U-velocity profiles of the single and the CTJ structures at X/D=1.0, 3.0, and 5.0 at Z/D=0.0

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Figure 13

Spanwise velocity profiles of the single and the CTJ structures at X/D=1.0, 3.0, and 5.0 at Z/D=0.0.

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Figure 14

Turbulent kinetic energy profiles at different X-locations: (a) X/D=3.0, (b) X/D=5.0, and (c) X/D=8.0

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Figure 15

Spanwise average and center line film cooling effectiveness

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Figure 16

Temperature contours at X/D=3.0 at different density ratios: (a) DR=0.5, (b) DR=1.0, (c) DR=2.0, (d) LMDR=2.0, and (e) LMDR=3.0

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Figure 17

Streamlines of the lateral-spanwise velocity components at X/D=3.0 at different density ratios: (a) DR=0.5, (b) DR=1.0, (c) DR=2.0, (d) LMDR=2.0, and (e) LMDR=3.0

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Figure 18

Film cooling effectiveness at different density ratios: (a) spanwise averaged and (b) centerline

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Figure 19

Streamlines of the lateral-spanwise velocity components at X/D=3.0 at different velocity ratios: (a) VR=1.0, (b) VR=2.0, and (c) VR=3.0

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Figure 20

Temperature contours at X/D=3.0 at different velocity ratios: (a) VR=0.5, (b) VR=1.0, (c) VR=2.0, and (d) VR=3.0

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Figure 21

Film cooling effectiveness at different velocity ratios: (a) spanwise averaged and (b) centerline

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