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題 名 | 船舶重柴油機活塞內冷卻通道於往復運動下熱傳現象之研究=Convective Heat Transfer of Reciprocating Ducts with Piston Cooling Application for Marine Diesel Engine |
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作 者 | 顏克家; | 書刊名 | 國立高雄海專學報 |
卷 期 | 12 1997.04[民86.04] |
頁 次 | 頁17-32 |
分類號 | 444.7 |
關鍵詞 | 往復流熱傳; 活塞冷卻; 柴油機; Pulsating convective heat transfer; Piston cooling; Diesel engine; |
語 文 | 中文(Chinese) |
中文摘要 | 本文發表一針對船舶重型柴油主機活塞冷卻通道於承受往復運動時其熱對流熱傳 特性之實驗研究結果。由於往復運動對於活塞冷卻通道熱傳性能會產生可觀之改變,因此於 設計船舶重型柴油機活塞內冷卻系統時必須審慎考慮往復運動對其冷卻性能之影響。 為採討此往復動對於活塞冷卻通道傳性能之影響進而評估可能增進活塞冷卻性能之可行方案 ,一具有平滑表面之圓管及一兩端封閉且其表面加設突起物之方形實驗測試段均被採用以研 究往復運動對其熱傳性能之影響。於實驗進行前,一引用往復座標系描述流體動員方程之理 論分析必須完成以確定控制該類流場熱傳特性無因次參數之組成;並應用此類無因次參數訂 定一實驗檢測之參數範圍及作為實驗原始數據機處理之依據。經由此次實驗結果證明,引用 管壁內設突起物之強制熱對流係數於非往復情下其熱傳係數約為平滑管之 235%。 往復運動 之引入有助於提昇平滑管之熱傳性能。 對於方形內設突起物封閉區間 (square ribbed enclosure) 而言, 於低往復力情形下往復運動會降低於進口端之熱傳係數。 對流場下游 (flow downstream locations) 而言或繼續增加往復力之強度,則往復運動將可提昇其熱傳 性能。針對浮力對熱傳現象之影響而言,強制對流下平滑管及內設突起物之非往復熱傳數據 並未因浮力強度之變化產生可觀改變。於方形內設突起物封閉區間內,由於熱對流現象造成 流體密度改變進而引起浮力效應。相當可觀之浮力影響可由實驗結果確認。對往復狀態而言 ,增加浮力強度可提高平滑管乃方形內設突起物封閉區間之熱傳性能。 |
英文摘要 | This paper presents the results obtained from an experimental program aimed at investigating the heat transfer phenomena taking place within the reciprocating coolant passages with particular cooling applications for the piston of marine heavy diesel engine. A smooth-walled circular tube and a rib-roughened square enclosure were used to study the influences. of reciprocating forces on the convective heat transfer. prior to the experimentation, a theoretical study which employed a reciprocating reference frame of coordinates was performed to formulate the flow momentum equations. The dimensionless flow parameters which characterized the heat transfer mechanism were accordingly defined. These dimensionless groups were used to define the parametric ranges tested and for the subsequent data processing. Based on the experimental results obtained, about 235% of the equivalent smooth-walled heat transfer values for the ribbed duct flow could be achieved when the flow within the ribbed duct was forced convective. The introduction of pulsating forces tended to increase heat transfer level for smooth-waled test tube. Within the ribbed enclosure, the reciprocating force reduced the heat transfer enhancement relative to the equivalent stationary situation occurred. The buoyancy effect for forced convective smooth-walled and rib-roughened duct flow was not considerable. But, for the ribbed enclosure, the considerable buoyancy effects were found. For both smooth-walled tube flow and the fully trapped flow within the ribbed enclosure, the increase of buoyancy levels improved the Heat transfer performances, Due to the significant heat transfer modifications provided bythe pulsating forces for the reciprocating ductflows, the influences of reciprocating motion on the heat transfer have to be carefully considered during the design stage of a piston for marine heavy dieselengine in order to achieve the optimal design of a diesel engine. |
本系統中英文摘要資訊取自各篇刊載內容。