衝擊流中紊流產生器對熱傳及流場特性探討

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Title:	衝擊流中紊流產生器對熱傳及流場特性探討
Other Titles:	Heat Transfer and Flow Characteristics in Impinging Flows with Turbulators
Authors:	李嘉慶;陳增源
Contributors:	淡江大學航空太空工程學系
Keywords:	熱傳;衝擊流;渦流產生器;Heat transfer;Impinging flow;Turbulator
Date:	2003-12
Issue Date:	2014-03-07 09:02:17 (UTC+8)
Abstract:	本研究實驗探討衝擊流中，紊流產生器對流場結構及熱傳之影響。衝擊流特性係利用一77cm/sup 2/管道，其一端連接一風洞系統，在管道入口產生一均勻流，而管道另一端中央置有一垂直於流場、44cm/sup 2/之加熱板，用來當作熱傳面；在管道入口附近、左右側壁置於成對之紊流產生器，包括有45°與90°矩形板及三角翼四種。研究中以雷射測速儀量測管道軸向斷面及靠近熱傳面三方向之平均及擾動速度，以獲得近熱傳面之軸向平均速度、軸向渦流及擾動動能。而熱傳面之溫度由熱電偶絲（Thermocouple）量測，藉以獲得Nusselt number。實驗結果顯示在衝擊流中加裝紊流產生器會增加近熱傳面之軸向平均速度、軸向渦流及擾動動能，並造成熱傳之增益，其熱傳增益雷諾數增加而增加，且90°矩形板紊流產生器有最好之熱傳增益。 The flow and heat transfer characteristics in impinging flows with turbulators were experimentally investigated. A uniform flow was generated at the inlet of a 77cm/sup 2/ duct by a wind tunnel, and a 44cm/sup 2/ heat transfer plate was placed at the other end of the duct for heat transfer surface, perpendicular to the incoming flow. A Pair of turbulator was mounted on the left and right duct walls near the inlet of the duct, which included rectangular-plate and triangular-plate turbulators, 45� and 90� angle of attack. The studies included three-component mean and fluctuating velocity measurements at duct axial cross-section and near the heat transfer surface using laser Doppler velocimetry. The axial vorticity, turbulent kinetic energy and axial mean velocity near the heat transfer surface were obtained from the measured velocity data. The temperatures on the heat transfer surface were measured using type-T thermocouples to obtain the Nusselt numbers. Results show that the turbulators in impinging flows have the effect to increase the axial vorticity, turbulent kinetic energy and averaged axial mean velocity and, thus, to augment the heat transfer. The heat transfer augmentation increases with increasing Reynolds numbers, and the 90� rectangular-plate turbulator causes the largest heat transfer augmentation among the investigated turbulators.
Relation:	2003年中國航空太空學會/中華民用航空學會學術研討會論文集(下冊)，頁1334-1340
Appears in Collections:	[Graduate Institute & Department of Aerospace Engineering] Proceeding

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