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Research Papers: Jets, Wakes, and Impingment Cooling

Flow and Heat Transfer Characteristics of Single Jet Impinging on Dimpled Surface

[+] Author and Article Information
Di Zhang

Associate Professor
e-mail: zhang_di@mail.xjtu.edu.cn
Key Laboratory of Thermo-Fluid Science and Engineering,
Ministry of Education,
School of Energy and Power Engineering,
Xi'an Jiaotong University,
Xi'an, Shaanxi Province 710049, China

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received July 1, 2012; final manuscript received January 5, 2013; published online April 11, 2013. Assoc. Editor: Phillip M. Ligrani.

J. Heat Transfer 135(5), 052201 (Apr 11, 2013) (15 pages) Paper No: HT-12-1341; doi: 10.1115/1.4023360 History: Received July 01, 2012; Revised January 05, 2013

Based on combined particle image velocimetry (PIV) and numerical simulation, the flow and heat transfer characteristics of a single jet impinging on a dimpled surface for Dj/D = 0.318, 0.5, 1.045; δ/D = 0.1, 0.2, 0.3; Rej = 5000, 10,000, 23,000, were investigated for the first time. The distance between jet nozzle and plate was fixed and equal to H/D = 2. The results show that the flow structures of the single jet impingement with dimpled target surface can be summarized into three typical conceptual flow structures. Particularly, the third flow structure in the form of a large toroidal vortex bound up with the dimple is the result of the centrifugal force of the flow deflection at the stagnation region and spherical centrifugal force of the deep dimple surface. The heat transfer area increases when the dimple relative depth increases. For the cases of Dj/D = 0.318 and 0.5, the area increasing dominate the heat transfer process, and the average Nusselt number increases with the increasing of dimple relative depth. For the cases with Dj/D = 1.045, the local Nusselt number reduction dominate the heat transfer process, the average Nusselt number decreases with the increasing of dimple relative depth. The average Nusselt number of the Dj/D = 0.318 and 0.5 cases is larger than the baseline case, while those of the Dj/D = 1.045 cases are smaller than the baseline case. Furthermore, the correlative expressions of the local Nusselt number, stagnation points Nusselt number and average Nusselt number are obtained.

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References

Figures

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Fig. 4

Computational domain

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Fig. 7

Jet velocity contours on the dimpled target (left: PIV, right: CFD): (a) Dj/D = 0.318, δ/D = 0.1, Rej = 5000, (b) Dj/D = 0.318, δ/D = 0.2, Rej = 5000, and (c) Dj/D = 0.318, δ/D = 0.3, Rej = 5000

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Fig. 8

Jet vorticity contour and streamlines on the dimpled target (left: PIV, right: CFD): (a) Dj/D = 0.318, δ/D = 0.1, Rej = 10,000, (b) Dj/D = 0.318, δ/D = 0.2, Rej = 10,000, and (c) Dj/D = 0.318, δ/D = 0.3, Rej = 10,000

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Fig. 3

Test plate and dimensions of dimple: (a) the test plate and (b) cross-sections of dimple

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Fig. 2

Schematic diagram of impingement on the dimpled target (Dj/D = 0.318, δ/D = 0.2, H/Dj = 2)

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Fig. 1

Schematic diagram of experimental system: (a) whole experimental system and (b) schematic diagram of PIV laser sheet

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Fig. 14

Numerical static pressure contour (left), velocity contour (right) and streamlines when Dj/D = 0.318, Rej = 23,000: (a) δ/D = 0.1, (b) δ/D = 0.2, and (c) δ/D = 0.3

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Fig. 5

Comparison of local Nusselt number between different turbulence model and experimental results

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Fig. 6

Vorticity contour and streamlines of impingement on the dimpled target (left: PIV, right: CFD): (a) Dj/D = 0.318, δ/D = 0.1, Rej = 5000, (b) Dj/D = 0.318, δ/D = 0.2, Rej = 5000, and (c) Dj/D = 0.318, δ/D = 0.3, Rej = 5000

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Fig. 9

Jet vorticity contour and streamlines on the dimpled target (left: PIV, right: CFD): (a) Dj/D = 0.318, δ/D = 0.1, Rej = 23,000, (b) Dj/D = 0.318, δ/D = 0.2, Rej = 23,000, and (c) Dj/D = 0.318, δ/D = 0.3, Rej = 23,000

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Fig. 10

Jet impingement vorticity contour on the dimpled target (left: PIV, right: CFD) (Dj/D = 0.5, δ/D = 0.2, Re = 23,000)

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Fig. 11

Jet vorticity and streamlines on the dimpled target (left: PIV, right: CFD): (a) Dj/D = 1.045, δ/D = 0.3, Rej = 5000, (b) Dj/D = 1.045, δ/D = 0.3, Rej = 10,000, and (c) Dj/D = 1.045, δ/D = 0.3, Rej = 23,000

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Fig. 12

Dj/D = 0.318, the numerical pressure distribution on the dimpled target with different δ/D and Rej: (a) overall pressure coefficient distribution and (b) local pressure distribution in the dimple periphery region

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Fig. 15

Dj/D = 0.5, numerical pressure coefficient distribution on target with different δ/D and Rej

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Fig. 16

Numerical pressure contour (left), velocity contour (right), and streamlines when Dj/D = 0.5, Rej = 23,000, δ/D = 0.2

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Fig. 26

The numerical local Nusselt number distribution when Dj/D = 1.045

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Fig. 17

Dj/D = 1.045, numerical pressure coefficient distribution on target with different δ/D and Rej

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Fig. 18

Numerical pressure contour (left), velocity contour (right), and streamlines when Dj/D = 1.045, Rej = 10,000, δ/D = 0.3

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Fig. 19

Concept map of impingement flow on the dimpled target: (a) concept map 1, (b) concept map 2, and (c) concept map 3

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Fig. 25

The numerical local Nusselt number distribution when Dj/D = 0.5

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Fig. 13

Turning angle (90 + β) between the dimple edge and target

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Fig. 27

The value of stagnation point Nusselt number

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Fig. 28

The average Nusselt number inside the dimple cavity

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Fig. 20

The numerical local Nusselt number distribution when Dj/D = 0.318

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Fig. 21

Numerical velocity and TKE profiles departing from the dimple when Dj/D = 0.318, δ/D = 0.1, Rej = 5000: (a) velocity distribution and (b) TKE distribution along the normal direction of wall

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Fig. 22

Dj/D = 0.318, δ/D = 0.1, Rej = 23,000, numerical velocity and TKE profiles departing from the dimple: (a) velocity distribution and (b) TKE distribution along the normal direction of wall

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Fig. 23

Dj/D = 0.318, δ/D = 0.2, Rej = 23,000, numerical velocity and TKE profiles departing from the dimple: (a) velocity distribution, (b) TKE distribution along the normal direction of wall, and (c) velocity vector and the TKE contour

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Fig. 24

Numerical TKE distribution contour near the impingement flow when Dj/D = 0.318, δ/D = 0.3, Rej = 23,000

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