Effect of gap lenghts of sphere-sphere electrodes on air breakdown level under lightning impulse
Impinging jets are a best method of achieving particularly high heat transfer coefficient and are therefore employed in many engineering applications. In this study we seek to understand the mechanism of the distributed heat on the curve surface with the goal of identifying preferred methods t...
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| Format: | Thesis |
| Language: | English English English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/1429/1/24p%20AHMAD%20AZLAN%20HAMZAH.pdf http://eprints.uthm.edu.my/1429/2/AHMAD%20AZLAN%20HAMZAH%20COPYRIGHT%20DECLARATION.pdf http://eprints.uthm.edu.my/1429/3/AHMAD%20AZLAN%20HAMZAH%20WATERMARK.pdf |
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| Summary: | Impinging jets are a best method of achieving particularly high heat transfer
coefficient and are therefore employed in many engineering applications. In this
study we seek to understand the mechanism of the distributed heat on the curve
surface with the goal of identifying preferred methods to predicting jet performance.
The goals that have been achieved in the numerical results displayed are
determine the influence of impingement jet characteristics on thermal and flow field
on a curve surface, determine the variation of Nusselt numbers (NuD) along the
curve surface in order to understand the heat transfer characteristics and study the
effect of position (in the center, in the mid and in the end) and angle (α=90°, 60° and
30°) of jet impingement on curve surface, different Reynolds numbers (ReD) in
range of (5000, 6000, 7000, 8000 and 9000). The program, which was extracted
results it is (GAMBIT 2.4.6) and (FLUENT 6.3), simulation is (2-D) in submerged
jet flow and the continuity, momentum and energy equations were solved by means
of a finite volume method (FVM).
This study covers the effect of different Reynolds numbers (ReD) on average
Nusselt numbers (Nuavg) and local Nusselt numbers (NuD). From the result, the
average Nusselt numbers (Nuavg) increased with the increase of Reynolds numbers
(ReD) for all cases, in comparison between different positions (center, mid and end),
of nozzle on curve surface at angle (α=90°) the maximum value of average Nusselt
numbers (Nuavg=388.3) is found when the nozzle locate in the end followed by the
mid position and smallest value of average Nusselt numbers (Nuavg=182.25) in the
center of curve surface. In case of slant angle (α=60º) the maximum value of average
Nusselt numbers (Nuavg=387.47) is found when the nozzle locate in the end
followed by the mid position and smallest value of average Nusselt numbers
(Nuavg=308.3) in the center of curve surface. |
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