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研究生:邱漢儒
研究生(外文):Han-Ru Chiu
論文名稱:熔融液滴撞擊壁面之凝固現象探討
論文名稱(外文):The theoretical solidification models of a melt droplet impinging on a cold surface
指導教授:馬小康馬小康引用關係
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:機械工程學研究所
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2004
畢業學年度:92
語文別:中文
論文頁數:71
中文關鍵詞:液滴撞擊擴張因子飛濺參數最大擴張速度厚凸參數
外文關鍵詞:spread factoravioding parameterdroplet impingingsplash criterionmaximun spread velocity
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在此之前,關於無凝固現象之液滴撞擊壁面之擴張因子之預測理論模式,已有先進獲得與實驗頗為相近之預測模式。而當壁面溫度低於液滴凝固點時,於擴張過程中將伴隨凝固之現象。本文即應用能量守恆、質量守恆及流率守恆等原理並植基於等溫壁面,進一步建構伴有凝固現象之擴張因子之理論預測模式。於此為簡化模式,乃僅考慮液滴本身之熱力及物理性質而忽略壁面者。另慮及凝固之發生乃於擴張過程中即伴隨著進行,故引入凝固時間修正因子於擴張因子之預測模式中,以符合實際狀況,並改善預測誤差。除此之外,本文尚試者推導出飛濺參數, ;避免液膜中心厚度凸起之參數, >0.5;及最大徑向擴張速度, 。以上之理論模式分析結果與實驗數據或其他模式相較,誤差約於10%之內。
The predictive theoretical model which investigates the spread factor of a droplet impinging solid surface without solidification had been developed, and had got well agreement with experiments by the previous works[8,10]. In the case that wall temperature is less than the solidification point of droplets,solidification would happen simultaneously. So the present study aims to develop another resemble theoretical model in which considers solidification, based on isothermal surface through the laws of continuity, energy conservation, and flow rate conservation. The developed model mainly focuses on the physical and thermodynamic properties of droplet, ignores that of surface in order to simplify the model. A time correcting factor is introduced into the spread factor model to account for the reality that the solidification of droplet accompanies with spreading,and which may improve its prediction. In addition, several theoretical models are also constructed in the study as follows: splashing criterion, ; avoiding parameter for central prominence of splat, >0.5; and maximum spread speed, . The present study has shown a well agreement to experiments or other models within about 10% error analysis.
總目錄

中文摘要 ............................................ i
英文摘要 ............................................. ii
目錄 ................................................. iii
圖表目錄 ............................................. iv
符號說明 ............................................. vi
目錄
第一章 緒論 ......................................... 1
1.1 研究動機 ................................ 2
1.2 研究目的 ............................... 3
第二章 文獻回顧 ...................................... 4
第三章 理論模式 ...................................... 8
3.1 凝固厚度成長方程式 ...................... 8
3.2 凝固時間修正 ............................12
3.2.1 凝固時間方程式 ...............13
3.2.2 徑向擴張時間方程式 ........... 15
3.2.2.1 徑向擴張速度方程式 16
3.2.2.2 徑向擴張加速度方程 20
3.2.2.3 徑向擴張時間 ...... 21
3.2.2.4 時間修正因子 ...... 23
3.3 有凝固現象下之液滴最大擴張因子............24
3.4 凝固厚度均勻性 ........................ 28
3.5 沉積之飛濺(splash)判斷標準 ............ 29
第四章 結果與討論 ................................... 32
4.1凝固厚度之成長 ........................... 32
4.2 凝固時間修正............................. 34
4.2.1 凝固速度與凝固時間 ........... 34
4.2.2 擴張速度與時間 ............... 35
4.3 最大擴張因子 ............................ 36
4.4 厚度均勻性 .............................. 39
4.5 飛濺(splash)判斷 ...................... 41
第五章 結論與建議 .................................... 43
參考文獻 ............................................. 46

圖表目錄

圖1 本文建立之兩凝固厚度成長方程式(12)及(46)之凝固厚度隨時間成長之比較,Re=6140,錫滴...................... 49
圖2 本文建立之兩凝固厚度成長方程式(12)及(46)之凝固厚度隨時間成長之比較,Re=7650,錫滴...................... 49
圖3 本文建立之兩凝固厚度成長方程式(12)及(46)之凝固厚度隨時間成長之比較,Re=12285,錫滴..................... 50
圖4 本文建立之兩凝固厚度成長方程式(12)及(46)之凝固厚度隨時間成長之比較,Re=18430,錫滴..................... 50
圖5 不同之凝固厚度成長方程式(12)與(46)於不同Re number下之凝固厚度成長之演化................................... 51
圖6 直徑2.1 mm,撞擊初速1.6 m/s之錫滴,四種模式與解析解之凝固厚度之比較.......................................... 52
圖7 直徑2.7 mm,撞擊初速1.0 m/s之錫滴,四種模式之凝固厚度比較.................................................... 53
圖8 直徑2.7 mm,撞擊初速3.0 m/s之錫滴,四種模式之凝固厚度比較.................................................... 53
圖9 不同壁面溫度與Ste number及凝固厚度之關係.......... 54
圖10 凝固速度與時間之關係............................. 54
圖11 錫滴於不同Re number下凝固時間之變化.............. 55
圖12 錫滴於不同We number下凝固時間之變化.............. 55
圖13 不同之撞擊速度變化假設下,徑向速度之變化情形..... 56
圖14 最大擴張因子與最大擴張(徑向)速度之關係......... 56
圖15 於不同Re number下,式(62)與無凝固現象之最大擴張因子之比較.................................................. 57
圖16 於不同Re number下,式(63)與無凝固現象之最大擴張因子之比較.................................................. 57
圖17 本文建立之兩伴有凝固之最大擴張因子方程式(62)與 (63)於不同Re number下之 預測比較......................... 58
圖18 本文建立之兩伴有凝固之最大擴張因子方程式(62)與(63)於不同We number下之 預測比較.............................58
圖19 伴有凝固之最大擴張因子方程式(62)與(63)之Re0.25與最大擴張因子之關係........................................ 59
圖20 各模式於不同Re number下之最大擴張因子與實驗數據之比較,錫滴.............................................. 60

圖21 各模式之最大擴張因子與實驗數據比較之誤差......... 61
圖22 不同壁面溫度與最大擴張因子之關係................. 62
圖23 擴張半徑與凝固厚度隨時間之變化................... 63
圖24 本理論擴張完畢瞬間之凝固斷面半視圖............... 63
圖25 各比能量項於不同撞擊初速下之變化,錫滴............64
圖A1 撞擊初速2 m/s之錫滴撞擊壁溫分別為25℃、150℃及240℃之不�袗�板之過程影像[10].................................65
圖A2 撞擊初速分別為1 m/s、2 m/s及4 m/s之錫滴撞擊壁溫為25℃之不�袗�板之過程影像[10]...............................66
圖A3 不同撞擊初速之錫滴撞擊25℃不�袗�板之擴張實驗過程[10]
.......................................................67
圖A4 不同撞擊初速之錫滴撞擊不同壁溫之最大擴張因子之實驗數據[10].................................................. 67
圖A5 錫滴撞擊實驗之接觸角之變化[10]................... 68
圖A6 撞擊徑向流之波前堆積現象[15]..................... 69
圖A7 不同壁面溫度下之無因次化最大擴張速度[11](圖中a相當本文中之 ).................................................70
表1 本文飛濺參數與Mundo飛濺參數之比較................. 71
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