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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Heat Transfer Enhancement for Row of Impinging Jets in Cross-Flow with Some Baffle Attachments

Get access (open in a dialog) DOI: 10.1615/IHTC15.ipj.009385
pages 4607-4620

Sinopsis

The aim of this research is to study the effect of mounting baffles on heat transfer enhancement for a row of impinging jets within cross-flow. A row of 4 air jets was directly discharged from round orifices with on inline arrangement and impinged on the inner surface of the rectangular wind tunnel. The orifice diameter (D) was 13.2 mm, jet-to-impingement surface distance and jet-to-jet distance were fixed at H=2D and S=3D, respectively. To study the effect of the cross-flow, the jet velocity was fixed at 15 m/s (Re=13,400) and the cross-flow velocity was varied corresponding to the velocity ratio (jet velocity /cross-flow velocity) at VR=3, 5 and 7. A pair of rectangular baffles each with length of 1.3D, height of 0.6D and thickness of 3 mm was attached in a Vshaped arrangement on the surface on the upstream side of each impinging jet. The angle of attack was defined as an angle between the baffle to the cross-flow and was varied to give ?=30o, 45o and 60o. The heat transfer characteristic was visualized by using a Thermochromic Liquid Crystal sheet (TLCs) and the Nusselt number was evaluated by using image processing method. Numerical simulation was also employed to investigate the flow field. The results show that the heat transfer rate for the case with baffle attachment at ?=60o is higher than the case of no baffle attachment by about 55.32%, 29.3% and 18.63% for VR=3, 5 and 7, respectively. This is due to the baffle attachment promoting the turbulence intensity in the jet flow before impingement.