Research Papers: Forced Convection

Effect of Rounded Corners on Heat Transfer and Fluid Flow Through Triangular Duct

[+] Author and Article Information
Rajneesh Kumar

Mechanical Engineering Department,
National Institute of Technology,
Hamirpur 177005, India
e-mail: rajneesh127.nith@gmail.com

Anoop Kumar

Mechanical Engineering Department,
National Institute of Technology,
Hamirpur 177005, India
e-mail: anoop@nith.ac.in

Varun Goel

Mechanical Engineering Department,
National Institute of Technology,
Hamirpur 177005, India
e-mail: varun7go@gmail.com

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received January 24, 2018; final manuscript received July 13, 2018; published online August 28, 2018. Assoc. Editor: Danesh K. Tafti.

J. Heat Transfer 140(12), 121701 (Aug 28, 2018) (10 pages) Paper No: HT-18-1048; doi: 10.1115/1.4040957 History: Received January 24, 2018; Revised July 13, 2018

Turbulent flow heat transfer and friction penalty in triangular cross-sectional duct is studied in the present paper. The sharp corners of the duct are modified by converting it into circular shape. Five different models were designed and fabricated. Heat transfer through all the models was investigated and compared conventional triangular duct under similar conditions. The curvature radius of rounded corners for different models was kept constant (0.33 times the duct height). The numerical simulations were also performed and the obtained result validated with the experimental findings and close match observed between them. The velocity and temperature distribution is analyzed at particular location in the different models. Because of rounded corners, higher velocity is observed inside the duct (except corners) compared to conventional duct. Considerable increase in Nusselt number is seen in model-5, model-4, model-3, and model-2 by 191%, 41%, 19%, and 8% in comparison to model-1, respectively, at higher Reynolds number (i.e., 17,500). But, frictional penalty through the model-5, model-4, model-3, and model-2 increased by 287%, 54%, 18%, and 12%, respectively, in comparison to model-1 at lower Reynolds number (i.e., 3600).

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Fig. 1

Schematic flow diagram of experimental setup

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Fig. 2

Schematic view of different models examined in present work. (a) Model 1 (simple triangular duct), (b) Model 2 (triangular duct with one rounded corner), (c) Model 3 (triangular duct with two rounded corners), (d) Model 4 (triangular duct with three rounded corners), and (e) Model 5 (all corners are rounded and roughness on the heat conducting side of the duct).

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Fig. 3

Pictorial view of dimple-shaped protruded heat conducting side

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Fig. 4

Location of thermocouples placed on heat conducting side of the duct

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Fig. 5

Geometry with symmetry about a plane

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Fig. 6

Schematic of designed geometry with boundary conditions for performing simulations in case of the model 5

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Fig. 7

Meshed computational domain with inflation

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Fig. 8

Variation of dimensionless velocity in the duct at axial length of z/ltest = 0.75

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Fig. 9

Variation of dimensionless temperature in the duct at axial length of z/ltest = 0.75

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Fig. 10

Variation of Nuavg with Re in different models

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Fig. 11

Variation of f with Re for different models

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Fig. 12

Variation of sgen with Re for different models

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Fig. 13

Variation of Nu with Re for different x/e values

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Fig. 14

Variation of f with Re for different x/e values



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