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題 名 | 液滴撞擊加熱平板之模態分析=Pattern Analysis of a Single Droplet Impinging onto a Heated Plate |
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作 者 | 王安邦; 林志宏; 陳祈彰; | 書刊名 | 力學 |
卷 期 | 17:1 2001.06[民90.06] |
頁 次 | 頁39-49 |
分類號 | 440.133 |
關鍵詞 | 微小液滴; 萊氏溫度; 加熱平板; 撞擊模態; 物理機制; Single droplet; Heated plate; Impingement patterns; Physical mechanism; |
語 文 | 中文(Chinese) |
中文摘要 | 液滴平板間之熱傳特性與液滴撞擊平板之動態特性間雖然存在相當程度的關聯性,但因前者之平均時間尺度比後者之時間尺度長甚多,本文由分析兩者之相關性過程,發現對後者之特性歸類不宜完全因循傳統根據對前者之歸類來處理。本文以實驗歸納撞擊韋伯數小於200以下之小酒精液滴撞擊加熱平板的特性模態,以力學的觀點將其分為五類:分別為〔I〕全潤濕型撞擊、〔II〕潤濕沸騰型撞擊,〔III〕過渡型撞擊、〔IV〕乾式反彈型撞擊以及〔V〕乾式反彈衛星分離型撞擊。前兩者歸屬為濕式撞擊,後兩者為乾式撞擊。本文之結果顯示在高撞擊韋伯數下,液滴之乾式撞擊臨界溫度遠低於傳統所認定之萊氏溫度;此臨界溫度為液滴撞擊韋伯數之函數;撞擊韋伯數愈低,乾式撞擊臨界溫度愈高;力學中之壓膜效應首次被用於此並圓滿詮釋低溫即可產生乾式彈跳之機制。撞擊韋伯數對乾式撞擊區域邊界之影響遠較其對濕式者之影響大。本文同時指出在時間序各撞擊特性模態相互間之轉變關係,並提供數值計算者一系統化而可靠之資料庫作為起始條件與將來比對之用。 |
英文摘要 | The time scale for measuring the heat transfer phenomena, such as the Leidenfrost phenomena, is much longer than the hydrodynamic transient period of droplet impinging onto a heated surface. However, the Leidenfrost temperature has been long since taken as the criterion to classify characteristic regimes for not only heat transfer but also hydrodynamic impact patterns of liquid/solid system in the literature. The impingement phenomena of a single droplet onto a heated plate for We < 200 were experimentally classified as five different patterns in this paper. They are [I] completely wet [II] wet film boiling [III] transition [IV] dry rebounding and [V] satellite dry rebounding impact patterns. The former two patterns are wet impact, and the latter two are dry impact. This work reveals that the hydrodynamic impact parameter influence the classification of characteristic impact patterns, especially for the dry impact patterns. For high impact Weber numbers, the dry impact happens on the surface temperature much lower than the commonly believed Leidenfrost temperature due to the squeeze film effect. The evolutions how the impact changes from on to another characteristic patterns are also discussed. This paper offers a systematic and reliable data base for future numerical simulations. |
本系統中英文摘要資訊取自各篇刊載內容。