Characteristics of heat transfer in impinging jets by control of vortex pairing

H. H. Cho, C. H. Lee, Y. S. Kim

Research output: Contribution to journalConference article

3 Citations (Scopus)

Abstract

The present study is conducted experimentally to obtain heat transfer characteristics on the impingement surface for controlled jets. Counterflowing or coflowing stream around the jet periphery is used to control the jet at the nozzle lip. The characteristics of flow and heat transfer are studied on two different jet nozzle exit flow conditions, including a fully developed turbulent tube flow and an uniform velocity distribution flow. The experiments are carried out for nozzle-to-plate distances of 2 to 8 nozzle diameters, jet Reynolds numbers in the range of 10,000 to 70,000, and main and secondary flow velocity ratios, R = ΔU/2Ū, of 0.45 to 1.86. The secondary counter- and co-flows change the flow instability conditions in the shear layers resulting in changes of heat transfer on the impingement surface. For secondary counterflows, heat transfer on the impingement surface is changed little for the small nozzle-to-plate distance of H/D = 2, but is enhanced on the stagnation region with reduction on the secondary peak region for H/D = 4. Augmentation of heat transfer on the stagnation region increases with increasing jet Reynolds numbers. For secondary coflows, the jet potential core extends far downstream due to inhibited development of the vortices, but the heat transfer is reduced significantly and the secondary peak appears downstream with increasing blowing rates.

Original languageEnglish
JournalAmerican Society of Mechanical Engineers (Paper)
Issue numberGT
Publication statusPublished - 1998 Jan 1
EventProceedings of the 1998 International Gas Turbine & Aeroengine Congress & Exhibition - Stockholm, Sweden
Duration: 1998 Jun 21998 Jun 5

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Vortex flow
Heat transfer
Nozzles
Reynolds number
Secondary flow
Pipe flow
Blow molding
Velocity distribution
Flow velocity
Experiments

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Cite this

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abstract = "The present study is conducted experimentally to obtain heat transfer characteristics on the impingement surface for controlled jets. Counterflowing or coflowing stream around the jet periphery is used to control the jet at the nozzle lip. The characteristics of flow and heat transfer are studied on two different jet nozzle exit flow conditions, including a fully developed turbulent tube flow and an uniform velocity distribution flow. The experiments are carried out for nozzle-to-plate distances of 2 to 8 nozzle diameters, jet Reynolds numbers in the range of 10,000 to 70,000, and main and secondary flow velocity ratios, R = ΔU/2Ū, of 0.45 to 1.86. The secondary counter- and co-flows change the flow instability conditions in the shear layers resulting in changes of heat transfer on the impingement surface. For secondary counterflows, heat transfer on the impingement surface is changed little for the small nozzle-to-plate distance of H/D = 2, but is enhanced on the stagnation region with reduction on the secondary peak region for H/D = 4. Augmentation of heat transfer on the stagnation region increases with increasing jet Reynolds numbers. For secondary coflows, the jet potential core extends far downstream due to inhibited development of the vortices, but the heat transfer is reduced significantly and the secondary peak appears downstream with increasing blowing rates.",
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Characteristics of heat transfer in impinging jets by control of vortex pairing. / Cho, H. H.; Lee, C. H.; Kim, Y. S.

In: American Society of Mechanical Engineers (Paper), No. GT, 01.01.1998.

Research output: Contribution to journalConference article

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AU - Lee, C. H.

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N2 - The present study is conducted experimentally to obtain heat transfer characteristics on the impingement surface for controlled jets. Counterflowing or coflowing stream around the jet periphery is used to control the jet at the nozzle lip. The characteristics of flow and heat transfer are studied on two different jet nozzle exit flow conditions, including a fully developed turbulent tube flow and an uniform velocity distribution flow. The experiments are carried out for nozzle-to-plate distances of 2 to 8 nozzle diameters, jet Reynolds numbers in the range of 10,000 to 70,000, and main and secondary flow velocity ratios, R = ΔU/2Ū, of 0.45 to 1.86. The secondary counter- and co-flows change the flow instability conditions in the shear layers resulting in changes of heat transfer on the impingement surface. For secondary counterflows, heat transfer on the impingement surface is changed little for the small nozzle-to-plate distance of H/D = 2, but is enhanced on the stagnation region with reduction on the secondary peak region for H/D = 4. Augmentation of heat transfer on the stagnation region increases with increasing jet Reynolds numbers. For secondary coflows, the jet potential core extends far downstream due to inhibited development of the vortices, but the heat transfer is reduced significantly and the secondary peak appears downstream with increasing blowing rates.

AB - The present study is conducted experimentally to obtain heat transfer characteristics on the impingement surface for controlled jets. Counterflowing or coflowing stream around the jet periphery is used to control the jet at the nozzle lip. The characteristics of flow and heat transfer are studied on two different jet nozzle exit flow conditions, including a fully developed turbulent tube flow and an uniform velocity distribution flow. The experiments are carried out for nozzle-to-plate distances of 2 to 8 nozzle diameters, jet Reynolds numbers in the range of 10,000 to 70,000, and main and secondary flow velocity ratios, R = ΔU/2Ū, of 0.45 to 1.86. The secondary counter- and co-flows change the flow instability conditions in the shear layers resulting in changes of heat transfer on the impingement surface. For secondary counterflows, heat transfer on the impingement surface is changed little for the small nozzle-to-plate distance of H/D = 2, but is enhanced on the stagnation region with reduction on the secondary peak region for H/D = 4. Augmentation of heat transfer on the stagnation region increases with increasing jet Reynolds numbers. For secondary coflows, the jet potential core extends far downstream due to inhibited development of the vortices, but the heat transfer is reduced significantly and the secondary peak appears downstream with increasing blowing rates.

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