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題名 | 往復運動對內設凸起物管流熱傳現象影響之實驗研究=Effect of Reciprocation on Heat Transfer for Ribbed Duct Flow |
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作 者 | 蘇樂梅; 楊春陵; 張始偉; 黃正清; | 書刊名 | 中國造船暨輪機工程學刊 |
卷期 | 17:4 1998.11[民87.11] |
頁次 | 頁45-57 |
分類號 | 444.7 |
關鍵詞 | 往復流熱傳; 凸起物管流; 活塞冷卻; Heat transfer of reciprocating flow; Ribbed duct flow; Piston cooling; |
語文 | 中文(Chinese) |
中文摘要 | 本文以實驗方法,探討大型船舶引擎之管流內設凸起物(Ribbed duct flow)時, 於往復狀態下之熱傳物理現象及其對提昇活塞內冷卻性能產生之效應。實驗之進行係以內設 凸起物之方管分別於 0,0.42 ,0.83, 1.25 及 1.675 Hz 之往復頻率下運動,而冷卻水流 雷諾數控制於 3000~9000 之紊流狀態。 實驗結果顯示出管中設有凸起物時,其任一位置之 熱傳係數,因受往復力之影響會隨時間而變化。流場因凸起物及往復力所引生之渦流運動, 將導致管流之時間平均熱傳係數 (Time-averaged Nusselt number), 依流向作起伏變化。 在實驗參數範圍內,提高往復力及雷諾數,均會增強突起物影響熱傳係數之效應。整體實驗 證明,往復狀態下之管流平均熱傳係數值,約為靜態平滑管之 2.5 至 4.5 倍。因此,於強 制對流下,往復運動之管中內設凸起物能顯著提昇其熱傳性能。 |
英文摘要 | This experimental study examined the heat transfer phenomena of reciprocating ribbed duct flow and its effectiveness on the improvement of cooling performance of piston. Heat transfer experiments at four reciprocating frequencies, namely 0,0.42,0.83,1.25 and 1.675 Hz with flow Reynolds numbers varied from 3000~9000 for each frequency tested, were performed. The experimental results demonstrated the time-varied local heat transfer variations as a result of pulsating force induced by duct reciprocation. Due to the vortical motions induced by the rib-associated flows and pulsating force, the distribution of time-averaged Nusselt number along the reciprocating ribbed duct followed a periodical wavy-like pattern. Within the parametric range tested, increases of the relative strength of pulsating force and Reynolds number significantly enhanced the effect of ribs on heat transfer. In general, the heat transfer levels with in the reciprocating ribbed test duct could be about 250~450% of the values for a non-reciprocating smooth-walled duct, so that the beneficial effects of ribs on the heat transfer improvement for the reciprocating duct flow were demonstrated. |
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