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Licensed Unlicensed Requires Authentication Published by De Gruyter July 29, 2017

Application and Design of Multi-Impingement Cooling Channel in Turbine Blade Trail Edge

  • Longfei Wang EMAIL logo , Fengbo Wen , Songtao Wang , Xun Zhou and Zhongqi Wang

Abstract

The numerical simulations are used to conduct the comparative study of pin-fins cooling channel and multi-impingement cooling channel on the heat transfer and flow, and to design the multi-impingement channel through the parameters of impinging distance and impingement-jet-plate thickness. The Reynolds number ranges from 1e4 to 6e4. The dimensionless impinging distance is 0.60, 1.68, 2.76, respectively, and the dimensionless impinging-jet-thickness is 0.5, 1.0, 1.5, respectively. The endwall surface, pin-fins surface, impinging-jet-plate surface are the three object surfaces to investigate the channel heat transfer performance. The heat transfer coefficient h and augmentation factor Nu/Nu0 are selected to measure the surface heat transfer, and the friction coefficient f is chosen to evaluate the channel flow characteristics. The impinging-jet-plate surface owns higher heat transfer coefficient and larger area than pin-fins surface, which are the main reasons to improve the heat transfer performance of multi-impingement cooling channel. Reducing the impinging distance can improve the endwall surface heat transfer obviously and enhance impingement plate surface heat transfer to some extent, decreasing the thickness of impinging-jet-plate can significantly increase its own heat transfer coefficient, which both all increase the cooling air flow loss.

PACS: 44.15.+a

Funding statement: This work was supported by the National Natural Science Foundation of China; [Grant No. 51206034].

Acknowledgment

The authors acknowledge the support ofNational Natural Science Foundation of China (Grant No. 51206034).

Nomenclature

A

heat transfer area (mm2)

Aˉ

heat transfer area ratio

d

pin-fin diameter (mm)

dj

jet hole diameter (mm)

D

hydraulic diameter (mm)

f

friction coefficient

h

heat transfer coefficient (W m−2 K−1)

hˉ

dimensionless form of the heat transfer coefficient

H

pin-fin height or impinging-jet-plate height (mm)

H1

thickness of solid heating wall (mm)

Lin

length of entrance region (48*d)

Lout

length of exit region (48*d)

Lc

length of pin-fins cooling channel (mm)

N

number of grids

Nu

Nusselt number hD/k

Nu0

Nusselt number in fully developed smooth walled turbulent pipe flow

Nu0

augmentation factor

Pr

Prandtl number of cooling air

q

heat flux ratio (W m−2)

Q

heat flux (W)

Re

channel inlet Reynolds number

S1

spanwise spacing between pin-fins (mm)

S2

streamwise spacing between pin-fins (mm)

T

temperature (K)

TKE

turbulence kinetic energy of cooling air (J kg−1)

tj

thickness of impinging-jet-plate (mm)

U

velocity in streamwise direction (m s−2)

W

channel width (mm)

Greek symbols
δ

impinging-jet-plate thickness (mm)

λ

thermal conductivity of cooling air (W m−1 K−1)

μ

viscosity of cooling air (kg m−1 s−1)

ρ

density of cooling air (kg m−3)

ξ

heat transfer weight of surface

hˉ

area-averaged heat transfer coefficient (W m−2 K−1)

S2

impinging distance (mm)

Δp

pressure difference between inlet and outlet of experimental region (pa)

Subscripts
j

multi-impingement cooling channel

p

pin-fins cooling channel

e,j

endwall surface of multi-impingement cooling channel

j,j

impinging-jet-plate surface of multi-impingement cooling channel

e,p

endwall surface of pin-fins cooling channel

p,p

pin-fins surface of pin-fins cooling channel

w

wall

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Received: 2017-07-03
Accepted: 2017-07-12
Published Online: 2017-07-29
Published in Print: 2020-08-27

© 2020 Walter de Gruyter GmbH, Berlin/Boston

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