Comparison of local nusselt number between steady and pulsating jet at different jet reynolds number

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Abstract

The study was carried out to determine the effect of pulsating frequencies exiting from a hot circular air jet on the local heat transfer of a flat impingement aluminium plate. The velocity profile of a steady heated circular air jet and pulsating air jet at frequencies of 10 and 20 Hz was measured in the first part of the study. The same set-up was used to measure the heat flux of the pulsating jet impinging on a flat aluminium plate. The heat flux of the heated air jet impinging on the plate was measured using a heat flux micro-sensor at radial positions between 0 to 12 cm away from the stagnation point. Measurement of the heat flux was used to calculate the local heat transfer coefficient and local Nusselt Number for steady air jet and for air jet pulsating frequencies of 10 and 20 Hz. The Reynolds number used were 16 000, 23 300 and 32 000. Results obtained show that the local Nusselt number calculated at all measurement point for pulsating jet were higher than the local Nusselt number for steady jet. The results for pulsating jet Nusselt number was higher than the steady jet Nusselt number for the value of frequencies measured are due to the higher localised heat transfer. The higher Nusselt number obtained at localized radial positions can be due to the higher instantaneous velocity as was shown from the velocity profile plotted in the first part of the experiment. The relationship between the two results shows that higher flow velocity and turbulence intensity gives higher localized heat transfer.

Original languageEnglish
Pages (from-to)384-393
Number of pages10
JournalWSEAS Transactions on Environment and Development
Volume5
Issue number5
Publication statusPublished - May 2009

Fingerprint

Nusselt number
Reynolds number
heat
air
heat flux
heat transfer
Heat flux
Air
Heat transfer
velocity profile
Aluminum
comparison
aluminum
stagnation
Flow velocity
flow velocity
Heat transfer coefficients
Turbulence
experiment
turbulence

Keywords

  • Heat transfer coefficient
  • Jet frequency
  • Nusselt number
  • Pulsating air jet
  • Reynolds number

ASJC Scopus subject areas

  • Environmental Science(all)
  • Geography, Planning and Development
  • Energy(all)

Cite this

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title = "Comparison of local nusselt number between steady and pulsating jet at different jet reynolds number",
abstract = "The study was carried out to determine the effect of pulsating frequencies exiting from a hot circular air jet on the local heat transfer of a flat impingement aluminium plate. The velocity profile of a steady heated circular air jet and pulsating air jet at frequencies of 10 and 20 Hz was measured in the first part of the study. The same set-up was used to measure the heat flux of the pulsating jet impinging on a flat aluminium plate. The heat flux of the heated air jet impinging on the plate was measured using a heat flux micro-sensor at radial positions between 0 to 12 cm away from the stagnation point. Measurement of the heat flux was used to calculate the local heat transfer coefficient and local Nusselt Number for steady air jet and for air jet pulsating frequencies of 10 and 20 Hz. The Reynolds number used were 16 000, 23 300 and 32 000. Results obtained show that the local Nusselt number calculated at all measurement point for pulsating jet were higher than the local Nusselt number for steady jet. The results for pulsating jet Nusselt number was higher than the steady jet Nusselt number for the value of frequencies measured are due to the higher localised heat transfer. The higher Nusselt number obtained at localized radial positions can be due to the higher instantaneous velocity as was shown from the velocity profile plotted in the first part of the experiment. The relationship between the two results shows that higher flow velocity and turbulence intensity gives higher localized heat transfer.",
keywords = "Heat transfer coefficient, Jet frequency, Nusselt number, Pulsating air jet, Reynolds number",
author = "Rozli Zulkifli and Kamaruzzaman Sopian and Shahrir Abdullah and Takriff, {Mohd Sobri}",
year = "2009",
month = "5",
language = "English",
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pages = "384--393",
journal = "WSEAS Transactions on Environment and Development",
issn = "1790-5079",
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T1 - Comparison of local nusselt number between steady and pulsating jet at different jet reynolds number

AU - Zulkifli, Rozli

AU - Sopian, Kamaruzzaman

AU - Abdullah, Shahrir

AU - Takriff, Mohd Sobri

PY - 2009/5

Y1 - 2009/5

N2 - The study was carried out to determine the effect of pulsating frequencies exiting from a hot circular air jet on the local heat transfer of a flat impingement aluminium plate. The velocity profile of a steady heated circular air jet and pulsating air jet at frequencies of 10 and 20 Hz was measured in the first part of the study. The same set-up was used to measure the heat flux of the pulsating jet impinging on a flat aluminium plate. The heat flux of the heated air jet impinging on the plate was measured using a heat flux micro-sensor at radial positions between 0 to 12 cm away from the stagnation point. Measurement of the heat flux was used to calculate the local heat transfer coefficient and local Nusselt Number for steady air jet and for air jet pulsating frequencies of 10 and 20 Hz. The Reynolds number used were 16 000, 23 300 and 32 000. Results obtained show that the local Nusselt number calculated at all measurement point for pulsating jet were higher than the local Nusselt number for steady jet. The results for pulsating jet Nusselt number was higher than the steady jet Nusselt number for the value of frequencies measured are due to the higher localised heat transfer. The higher Nusselt number obtained at localized radial positions can be due to the higher instantaneous velocity as was shown from the velocity profile plotted in the first part of the experiment. The relationship between the two results shows that higher flow velocity and turbulence intensity gives higher localized heat transfer.

AB - The study was carried out to determine the effect of pulsating frequencies exiting from a hot circular air jet on the local heat transfer of a flat impingement aluminium plate. The velocity profile of a steady heated circular air jet and pulsating air jet at frequencies of 10 and 20 Hz was measured in the first part of the study. The same set-up was used to measure the heat flux of the pulsating jet impinging on a flat aluminium plate. The heat flux of the heated air jet impinging on the plate was measured using a heat flux micro-sensor at radial positions between 0 to 12 cm away from the stagnation point. Measurement of the heat flux was used to calculate the local heat transfer coefficient and local Nusselt Number for steady air jet and for air jet pulsating frequencies of 10 and 20 Hz. The Reynolds number used were 16 000, 23 300 and 32 000. Results obtained show that the local Nusselt number calculated at all measurement point for pulsating jet were higher than the local Nusselt number for steady jet. The results for pulsating jet Nusselt number was higher than the steady jet Nusselt number for the value of frequencies measured are due to the higher localised heat transfer. The higher Nusselt number obtained at localized radial positions can be due to the higher instantaneous velocity as was shown from the velocity profile plotted in the first part of the experiment. The relationship between the two results shows that higher flow velocity and turbulence intensity gives higher localized heat transfer.

KW - Heat transfer coefficient

KW - Jet frequency

KW - Nusselt number

KW - Pulsating air jet

KW - Reynolds number

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