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Numerical Heat Transfer, Part A: Applications
An International Journal of Computation and Methodology
Volume 73, 2018 - Issue 3
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Original Articles

Flow structure and heat transfer characteristics of a 90°-turned pin-finned wedge duct with dimples at different locations

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Pages 143-162 | Received 18 Oct 2017, Accepted 20 Dec 2017, Published online: 23 Jan 2018
 

ABSTRACT

In this study, numerical simulations are performed to investigate the effect of dimple location on the flow structure and heat transfer characteristics in a 90°-turned channel with pin fins. Results of the flow structure, heat transfer on the endwall, and friction factor are included in this study. It is found that the dimple location has an impact on the flow structure and heat transfer both for the pin fins arranged with in-line and staggered layout. The horseshoe vortex near the pin fin is influenced by the location of the dimple. The dimple enhances the Nusselt number on the endwall surface significantly. In addition, the dimple location has an effect on the low-speed recirculation, impingement, and vortex which are generated by the dimple. However, the dimple has very limited effects on the friction factor for all cases. It is also found that the area goodness factor and volume goodness factor are improved by the dimple.

Nomenclature

CFD=

computational flow dynamics

TKE=

turbulent kinetic energy

dd=

dimple diameter (mm)

dp=

pin fin diameter (mm)

Dh=

hydraulic diameter of the inlet (mm)

f=

friction factor

f0=

friction factor in smooth channel

h=

heat transfer coefficient (W/m2 · K)

H1=

inlet height (mm)

H2=

outlet height (mm)

L1=

channel length (mm)

L2=

channel width length (mm)

L3=

outlet extent length (mm)

Nu=

Nusselt number

Nu0=

Nusselt number in smooth channel

Pr=

Prandtl number

Pin=

inlet total pressure (Pa)

Pout=

outlet total pressure (Pa)

q=

wall heat flux (W/m2)

Re=

Reynolds number

S1=

distance between the dimple and pin fin in the streamwise direction (mm)

S2=

distance between the dimple and pin fin in the spanwise direction (mm)

Sx=

pin fin streamwise spacing (mm)

Sy=

pin fin spanwise spacing (mm)

Tin=

inlet air temperature (°C)

δ=

dimple depth (mm)

λ=

thermal conductivity of air (W/m · K)

μ=

dynamic viscosity (Pa · s)

ρ=

density of air (kg/m3)

Nomenclature

CFD=

computational flow dynamics

TKE=

turbulent kinetic energy

dd=

dimple diameter (mm)

dp=

pin fin diameter (mm)

Dh=

hydraulic diameter of the inlet (mm)

f=

friction factor

f0=

friction factor in smooth channel

h=

heat transfer coefficient (W/m2 · K)

H1=

inlet height (mm)

H2=

outlet height (mm)

L1=

channel length (mm)

L2=

channel width length (mm)

L3=

outlet extent length (mm)

Nu=

Nusselt number

Nu0=

Nusselt number in smooth channel

Pr=

Prandtl number

Pin=

inlet total pressure (Pa)

Pout=

outlet total pressure (Pa)

q=

wall heat flux (W/m2)

Re=

Reynolds number

S1=

distance between the dimple and pin fin in the streamwise direction (mm)

S2=

distance between the dimple and pin fin in the spanwise direction (mm)

Sx=

pin fin streamwise spacing (mm)

Sy=

pin fin spanwise spacing (mm)

Tin=

inlet air temperature (°C)

δ=

dimple depth (mm)

λ=

thermal conductivity of air (W/m · K)

μ=

dynamic viscosity (Pa · s)

ρ=

density of air (kg/m3)

Additional information

Funding

Lei Luo acknowledges the financial support provided by the Natural Science Foundation of China (No. 51706051) and China postdoctoral science foundation funded project (No. 2017M620116).

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