A Numerical Study on the Heat Transfer Characteristics of Impinging Jet Flow in the Presence of Applied Magnetic Fields

2005 ◽  
Vol 29 (6) ◽  
pp. 653-661
Author(s):  
Hyun Goo Lee ◽  
Hyun Sik Yoon ◽  
Seung Do Hong ◽  
Man Yeong Ha
Keyword(s):  
Heat Transfer ◽  
Magnetic Fields ◽  
Numerical Study ◽  
Impinging Jet ◽  
Jet Flow ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Flow and Heat Transfer Characteristics of Impinging Jet from Expansion Pipe Nozzle with Air Entrainment Holes

2014 ◽  
Vol 931-932 ◽  
pp. 1213-1217 ◽  
Author(s):  
Natthaporn Kaewchoothong ◽  
Makatar Wae-Hayee ◽  
Passakorn Vessakosol ◽  
Banyat Niyomwas ◽  
Chayut Nuntadusit
Keyword(s):  
Heat Transfer ◽  
Infrared Camera ◽  
Air Entrainment ◽  
Impinging Jet ◽  
Ambient Air ◽  
Jet Flow ◽  
Heat Transfer Characteristics ◽  
Pipe Length ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

Flow and heat transfer characteristics of impinging jet from expansion pipe were experimentally and numerically investigated. The expansion pipe nozzle was drilled on expansion wall for increasing an entrainment of ambient air into a jet flow. The diameter of round pipe nozzle was d=17.2 mm and the diameter of expansion pipe was fixed at D=68.8 mm (=4d). The number of air entrainment holes was varied at 4, 6 and 8 holes, and the expansion pipe length was examined at L= 2d, 4d and 6d. In this study, the expansion pipe exit-to-plate distance was fixed at H=2d and the Reynolds number of jet was studied at Re=20,000. Temperature distribution on the impinged surface was acquired by using an infrared camera. The numerical simulation was carried out to reveal the flow field. The results show that the ambient air enters through the holes and subsequently blocked the entrainment of ambient air into the jet flow. It causes to enhance the heat transfer particularly at stagnation point higher than the case of conventional pipe: 4.68% for 4 holes at L=2d, 6.4% and 6.28% for 4 holes and without holes at L=4d and 5.48% for 8 holes at L=6d.

Experimental and Numerical Study on Flow Field and Heat Transfer Characteristics for a Periodically Unsteady Impinging Jet

2010 ◽  
Author(s):  
Jing-Wei Zhou ◽  
Li-Ping Geng ◽  
Yu-Gang Wang ◽  
Fei-Fei Hong
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Numerical Study ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Unsteady Jets ◽  
Hotwire Anemometry ◽  
Heat Transfer Improvement

An experimental investigation has been carried out to study the effect of unsteady periodically impinging jets on the flow field and heat transfer characteristics. The experiments are performed for steady jets and for typical periodical jets (i.e., sinusoidal and rectangular jets) at frequencies from 1.25 to 40Hz. The periodical jets are produced by a special mass flow rate controller. The investigation shows that the stagnation point heat transfer does not show any enhancement for the periodically impinging jets when the frequency is lower. Various signals of unsteady jets show distinguishing frequency dependences and the rectangular jet, which has a step change in signal function itself, is the most effective one for heat transfer improvement and the degree of enhancement is in the range 30–40% at frequency of 40 Hz. This increase is believed to be caused by higher oscillations and strong entrainments to the ambient fluid. The hotwire anemometry is used to measure the velocity at centerline of the nozzle and PIV is used to measure the phase-locked flow field of the periodically impinging jet. The flow field is also obtained by numerical simulation with CFD.

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