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Research Papers: Jets, Wakes, and Impingment Cooling

Heat Transfer Due to an Impinging Jet in a Confined Space

[+] Author and Article Information
G. Nasif

Department of Mechanical,
Automotive and Materials Engineering,
University of Windsor,
Windsor, ON N9B 3P4, Canada
e-mail: nasifg@uwindsor.ca

R. M. Barron, R. Balachandar

Department of Mechanical,
Automotive and Materials Engineering,
University of Windsor,
Windsor, ON N9B 3P4, Canada

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received July 4, 2013; final manuscript received July 21, 2014; published online August 26, 2014. Assoc. Editor: Jim A. Liburdy.

J. Heat Transfer 136(11), 112202 (Aug 26, 2014) (10 pages) Paper No: HT-13-1337; doi: 10.1115/1.4028242 History: Received July 04, 2013; Revised July 21, 2014

A numerical investigation using unsteady three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations with the k-ω SST (shear stress transport) turbulent model was conducted to determine the flow and thermal characteristics of an unsubmerged axisymmetric oil jet in air, impinging normally on to a heated flat disk with finite radius, bounded by cylindrical walls kept at constant temperature. A 10 mm thick disk subjected to a high uniform heat flux was located at impingement distances ranging from 40 to 80 mm from the nozzle exit, for nozzle exit diameters of d = 1.0, 2.0, and 4.0 mm. The volume of fluid (VOF) method with a high-resolution interface-capturing (HRIC) scheme was implemented in STAR-CCM+. A new methodology was developed to predict the stagnation zone and local heat transfer coefficients. Contrary to previous research, it is shown that the radial extent of the stagnation zone is not fixed but depends on the gradient of radial velocity along the disk. The normalized local Nusselt number profile along the disk radius is found to be weakly dependent on Reynolds number for a given nozzle size. It is also shown that the local Nusselt number is not uniform in the stagnation region as reported by experimental studies but depends on the distribution of the near-wall radial velocity gradient. Using the computational results, new correlations to predict the dimensionless radial velocity gradient and Nusselt number have been developed. The present correlations are dimensionally balanced, eliminating a deficiency in earlier correlations noted in the literature.

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References

Figures

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Fig. 1

Jet and film flow showing hydrodynamic evolution

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Fig. 3

Effect of domain confinement on local Nusselt number obtained for nozzle size d = 4.0 mm at H/d=15 and Red=12,000

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Fig. 2

Computational domain and relevant boundary conditions

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Fig. 6

Contours of radial velocity gradient ∂ur/∂r and radial extent of the stagnation zone for d = 2.0 mm at H/d=30; (a) Red=4000, (b) Red=8000, (c) Red=12,000 and (d) Red=16,000

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Fig. 5

Comparison of computed local Nusselt number with correlation given by Eq. (2); H = 60 mm, d=2 mm

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Fig. 4

Comparison of computed stagnation zone Nusselt number with correlation given by Eq. (1), for H=60 mm

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Fig. 13

Effect of Reynolds number on: (a) stagnation zone average temperature, (b) disk average temperature; H=60 mm

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Fig. 14

Contours of temperature for the constant heat flux disk, for different nozzle sizes and jet Reynolds numbers; H=60 mm

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Fig. 7

Dependence of: (a) stagnation point radial velocity gradient and (b) dimensionless radial velocity gradient, on the parameter uf/d

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Fig. 8

Variation of stagnation zone Nusselt number with Reynolds number

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Fig. 9

Local Nusselt number Nu normalized by Nuo, H=60 mm: (a) H/d = 60, (b) H/d = 30, (c) H/d = 15

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Fig. 10

Temperature distribution across the fluid film at three different locations downstream of the stagnation point, H=60 mm, Red = 12,000: (a) H/d = 30, (b) H/d = 15

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Fig. 11

Temperature distribution at the interface between the oil sheet and impinging surface, H=60 mm, Red = 12,000: (a) H/d = 30, (b) H/d = 15

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Fig. 12

Distribution of radial velocity beneath the stagnation region (A): (a) d = 1.0 mm, Red = 8000, (b) d = 2.0 mm, Red = 16,000, (c) d = 4.0 mm, Red = 16,000

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