Heat and Mass Transfer

, Volume 49, Issue 8, pp 1141–1158

Numerical simulations of heat transfer distribution of a two-pass square channel with V-rib turbulator and bleed holes

  • Sourabh Kumar
  • R. S. Amano
  • Jose Martinez Lucci
Original

Abstract

The blade tip region in gas turbine encounters high thermal loads due to temperature difference and hence efforts for high durability and safe operations are essential. Improved and robust methods of cooling are required to downgrade heat transfer rate to turbine blades. The blade tip regions, which are exposed to high gas flow, suffers high local thermal load which are due to external tip leakage. Jet impingement, pin cooling etc. are techniques used for cooling blades. A more usual way is to use serpentine passage with 180-degree turn. In this study, numerical simulation of heat transfer distribution of a two-pass square channel with rib turbulators and bleed holes were done. Periodical rib turbulators and bleed holes were used in the channel. The ribs arrangement were 60 degree V rib, 60 degree inverted V ribs, combination of 60 degree V rib at inlet and 60 inverted V rib at outlet section and combination of Inverted V at inlet and V rib at the outlet. The results were numerically computed using Fluent with Reynolds number of 12,500 and 28,500. Turbulence models used for computations were k-ω-SST and RSM. Temperature based and shear stress based techniques were used for heat transfer distribution prediction. The results for 60 degree V rib, 60 degree inverted V ribs were compared with the experimental results for validation of the results obtained. Detailed distribution shows distinctive peaks in heat transfer around bleed holes and rib turbulator. Comparisons of the overall performance of the models with different orientation of rib turbulator are presented. It is found that due to the combination of 60 degree inverted V rib in inlet and 60 V rib in outlet with bleed holes provides better heat treatment. It is suggested that the use of rib turbulator with bleed holes provides suitable for augmenting blade cooling to achieve an optimal balance between thermal and mechanical design requirements.

List of symbols

A

Wall surface area

B

Channel divider wall thickness

CL

Length scale for pipe flows

\(C_{\mu }\)

Turbulence model constant (0.09)

D

Bleed hole diameter

D

Channel width

Dh

Hydraulic diameter

e

Rib height

h

Heat transfer coefficient

k

Turbulence kinetic energy

kT

Fluid thermal conductivity

kp

Turbulence kinetic energy at node P

K

Kelvin

L

Channel length

Nu

Nusselt number

\(Nu_{o}\)

Nusselt number used for normalization

P

Rib pitch

P

Pressure

Pr

Prandtl number

PrT

Turbulent prandtl number

\(\dot{q}_{w}^{\prime \prime }\)

Wall heat flux

Re

Reynolds number, Re = ρ UiDh/μ

\(T_{w}\)

Wall temperature

T

Temperature

uiujuj

Velocity in i, j, k direction

Ui

Inlet velocity

Up

Velocity at node p

uu

Reynolds stress

V

Area averaged velocity

vv

Reynolds stress

ww

Reynolds stress

xixjxj

Spartial coordinate

Greek symbols

μ

Dynamic viscosity

ω

Specific dissipation rate

ε

Turbulent dissipation rate

ρ

Fluid density

τw

Wall shear stress

Subscripts

0

Fully developed flow channel

ave

Averaged/overall value

i

Inlet

o

Outlet

w

Wall

T

Turbulent

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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Sourabh Kumar
    • 1
  • R. S. Amano
    • 1
  • Jose Martinez Lucci
    • 1
  1. 1.Department of Mechanical EngineeringUniversity of Wisconsin–MilwaukeeMilwaukeeUSA

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