Abstract
本研究是以雷射全像干涉術實驗量測具不同肋條排列方式之矩形管流熱傳與摩擦特性，所探討之幾何形狀共分為四種形式：（一）具漸縮式入口與裝置對稱排列穿孔肋條之管道（IPT case);(二)具漸縮式入口與裝置交錯排列穿孔肋條之管道(SPT case)；(三)具漸縮式入口與裝置交錯排列實心肋條之管道(SST case)；(四)具漸縮式入口與裝置非貼壁式穿孔肋條之管道(DPO case)。實驗中應用之技術為全像干涉術，其具有不干擾流場之優點，而且配合熱電偶量得之參考溫度，可計算出流場全場之溫度分佈，並可進一步求得管道之局部熱傳係數分佈。本文將肋條節距固定為10，所要探討之變數為肋條高度與管道水力直徑比 0.081與0.106，肋條穿孔率0%與44%，流場雷諾數設定在5000-50000之間，以及對稱排列、交錯排列與單邊非貼壁式的肋條排列方式。在本文實驗條件下，實驗結果發現在裝置對稱及交錯排列肋條的管道內，若使用穿孔肋條可使其熱傳性能增加，但若是在裝置非貼壁式肋條的管道內使用穿孔肋條，會使其熱傳性能降低。另外,提高肋條的高度,均能使熱傳性能增加。而裝置對稱排列實心肋條的管道，其熱傳性能比裝置交錯排列實心肋條管道的熱傳性能高，但是，裝置對稱排列穿孔肋條與裝置交錯排列穿孔肋條的管道之熱傳性能相差不大。本研究並利用煙線法進行流場觀測，且將穿孔肋條引致熱傳增加之原因歸納如下：(一)由於穿孔肋條後緣產生多重噴流使得紊流強度增加導致熱傳增加；(二)由於從肋條上緣產生之剪應力層與壁面激烈交互作用導致熱傳增加；(三)流體流經上下肋條間所產生之加速作用導致熱傳增加。This experimental work is concerned with the characteristicsof heat transfer and friction in rectangular duct flows withvarious rib configura- tions. Four rib configurations areconsidered: (1) Periodic fully developed duct flows with in-line perforated ribs mounted on two opposite walls (IPTcase);(2) Periodic fully developed duct flows with staggeredperforated ribs mounted on two opposite walls(SPT case); (3)Periodic fully developed duct flows with staggered solidtype ribs mounted on two opposite walls (SST case); (4)Periodic fully developed duct flows with perforated ribsdetached from one wall (DPO case). Laser holographic inter-ferometry associated with thermocouple technique are employedin the local and average heat trans- fer measurements. Theparameters investigated are rib height-to-channel hydraulicdiameter ratio, rib open-area-ratios, Reynolds number, and therib arrangrments (staggered, in-line and detached ribalignments).