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Research Papers

Modified Body Force Model for Air Flow Through Perforated Floor Tiles in Data Centers

[+] Author and Article Information
Vaibhav K. Arghode

George W. Woodruff
School of Mechanical Engineering,
Georgia Institute of Technology,
Atlanta, GA 30332
e-mail: vaibhav.arghode@gmail.com

Yogendra Joshi

George W. Woodruff
School of Mechanical Engineering,
Georgia Institute of Technology,
Atlanta, GA 30332

1Corresponding author.

Contributed by the Electronic and Photonic Packaging Division of ASME for publication in the JOURNAL OF ELECTRONIC PACKAGING. Manuscript received October 17, 2015; final manuscript received April 15, 2016; published online May 16, 2016. Assoc. Editor: Pradip Dutta.

J. Electron. Packag 138(3), 031002 (May 16, 2016) (11 pages) Paper No: EP-15-1116; doi: 10.1115/1.4033464 History: Received October 17, 2015; Revised April 15, 2016

Generally, porous jump (PJ) model is used for rapid air flow simulations (without resolving the tile pore structure) through perforated floor tiles in data centers. The PJ model only specifies a step pressure loss across the tile surface, without any influence on the flow field. However, in reality, the downstream flow field is affected because of the momentum rise of air due to acceleration through the pores, and interaction of jets emerging from the pores. The momentum rise could be captured by either directly resolving the tile pore structure (geometrical resolution (GR) model) or simulated by specifying a momentum source above the tile surface (modified body force (MBF) model). Note that specification of momentum source obviates the need of resolving the tile pore geometry and, hence, requires considerably low computational effort. In previous investigations, the momentum source was imposed in a region above the tile surface whose width and length were same as the tile dimensions with a preselected height. This model showed improved prediction with the experimental data, as well as with the model resolving the tile pore geometry. In the present investigation, we present an analysis for obtaining the momentum source region dimensions and other associated input variables so that the MBF model can be applied for general cases. The results from this MBF model were compared with the GR model and good agreement was obtained.

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References

Figures

Grahic Jump Location
Fig. 1

(a) MBF model without blocked edges, (b) MBF model with blocked edges, (c) MBF region, (d) perforated tile, (e) pressure drop across a tile without blocked edges, (f) pressure drop across a tile with blocked edges, and (g) MBF region height estimation based on jet behavior

Grahic Jump Location
Fig. 2

(a)–(f) Comparison of GR and MBF model with different height for momentum source specification (H), (a) computational domain (tile size = 0.61 m × 0.61 m (2 ft × 2 ft), domain height = −0.31 m (1 ft) to + 1.98 m (6 ft 6 in.), domain width = 0.91 m (3 ft)), (b) D = 2.54 cm (1 in.) GR (base case), (c) H = 2D, (d) H = 4D, (e) H = 6D, (f) excess X-momentum, along the height, and (g) MBF model, choosing Fref = 25%, estimating the empirical constants: Cref, a, and b

Grahic Jump Location
Fig. 3

Comparison of GR and MBF models for different porosities (F) (a) GR, (b) MBF, (c) GR, (d) MBF, (e) GR, (f) MBF, (g) excess X-momentum for free jet array, (h) excess X-momentum for symmetrical single jet, (i) evaluating empirical constant n, Fref = 25%, (j) F = 11%, (k) F = 25%, and (l) F = 44%

Grahic Jump Location
Fig. 4

Comparison of contours of velocity magnitude from GR and MBF models for different tile edge blockage (B) (a) GR, (b) MBF, (c) GR, (d) MBF, (e) GR, (f) MBF, (g) excess X-momentum for free jet array, (h) excess X-momentum for free jet for open area except blockage, (i) estimating empirical constant m, (j) B = 0 cm (0 in.), (k) B = 3.81 cm (1.5 in.), and (l) B = 7.62 cm (3 in.)

Grahic Jump Location
Fig. 5

Comparison of contours of GR and MBF models for small pore sizes (D) (a) D = 0.32 cm (0.125 in.), GR model, (b) D = 0.32 cm (0.125 in.), MBF model, (c) D = 0.64 cm (0.25 in.), GR model, (d) D = 0.64 cm (0.25 in.), MBF model, (e) computational domain, and (f) excess X-momentum

Grahic Jump Location
Fig. 6

Comparison of GR and MBF models for different tile thickness (T/D) (a) GR, (b) MBF, (c) GR, (d) MBF, (e) GR, (f) MBF, (g) excess X-momentum for free jet array, (h) excess X-momentum for symmetrical single jet, (i) T/D = 0 K = 32.0, (j) T/D = 1 K = 19.4, and (k) T/D = 1 K = 19.5

Grahic Jump Location
Fig. 7

Comparison of contours of GR and MBF models for AB (a) GR, (b) MBF, (c) GR, (d) MBF, (e) tile (D = 2.54 cm (1 in.), F = 25%), (f) anterior, 2.54 cm (1 in.) below tile (D = 5.08 cm (2in.), F = 50%), and (g) excess X-momentum

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