陳延平臺灣大學：化學工程學研究所陳兆萱Chen, Jhao-SyuanJhao-SyuanChen2007-11-262018-06-282007-11-262018-06-282007http://ntur.lib.ntu.edu.tw//handle/246246/52145　　本研究之目的在於探討扁鋼胚連續鑄造程序中，電磁攪拌器所產生之電磁力對於鋼液流動與熱傳現象的影響。在鑄造時加入電磁攪拌器，主要目的可減少鑄造缺陷，提升鋼胚品質。本研究使用計算流體力學軟體FIDAP，計算注嘴內流場與鑄模內流場與溫度場，對於紊流現象以K-ε紊流模式進行模擬。 　　關於本研究所模擬之注嘴，其出口角度為向下5°、15°、25°之直管與伸縮管，將注嘴出口的結果，代入鑄模作為入口條件。探討未加電磁力及電磁攪拌器中心高度為模液面下12cm、24cm、36cm時，對於鑄模內流場與溫度場的影響，其結果顯示：(1)伸縮管注嘴較直管注嘴有效的消散由於閥門所造成的不對稱。(2)未加電磁力於鑄模之情況下，撞擊點深度隨著注嘴出口入射角度越向下而越深，溫度分佈沿著流動方向漸減，而直管注嘴出口的不對稱，使得其鑄模流場與溫度場亦不對稱。以伸縮管、開口角度為向下15°之注嘴為較佳設計。(3)當電磁攪拌器中心高度為模液面下24cm時，電磁力主導鋼液的流動，撞擊點有效提升至模液面下24公分左右，且其撞擊點較未加電磁力之鑄模對稱。模液面的流動受電磁力方向影響，為一逆時鐘之環流，其最大速度約為39cm/s，平均表面波動為1.9mm。其溫度分佈亦受到流動形式之影響，在靠近鑄模壁有環狀分佈，可推測加入電磁力後，凝殼的厚度會較均一。伸縮管、開口角度為向下25°之注嘴，擁有較小之F值，故為較佳的注嘴設計。(4)隨著EMS中心高度越高，模液面之最大速度與表面波動增加、撞擊點亦隨之提升，K值趨近於1，表示其流場較未加電磁力來得均一。由F值與撞擊點判斷，當電磁攪拌器中心高度為模液面下24公分時，為最佳EMS的中心高度。目錄 中文摘要 I 英文摘要 III 目錄 V 表目錄 IX 圖目錄 X 第一章　緒論 1 　　1-1　文獻回顧 4 第二章　理論模式 9 　　2-1　數學理論模式 9 　　　　2-1-1　理論假設 9 　　　　2-1-2　統御方程式 10 　　　　2-1-3　K-ε紊流模式 11 　　　　2-1-4　電磁力之數學計算 12 　　2-2　邊界條件 17 　　　　2-2-1　三維注嘴邊界條件 17 　　　2-2-3　三維鑄模邊界條件 18 　　2-3　比較模擬結果之計算因子 19 　　　　2-3-1　三維注嘴出口平均特性參數計算方式 19 　　　　2-3-2　模液面波動振幅轉換方程式 21 　　　　2-3-3　K值 22 　　　　2-3-4　F值 22 　　2-4　無因次法 23 第三章　計算軟體與數值解程序 26 　　3-1　FIDAP簡介 27 　　3-2　FIDAP處理問題的步驟 28 　　3-3　單相流體流動之分類 32 　　3-4　數值解法 33 　　　　3-4-1　空間離散與係數矩陣 33 　　　　3-4-2　三維元素與其微分及積分 35 第四章　結果與討論 37 　　4-1　注嘴之流場模擬結果 38 　　　　4-1-1　比較nozA5d、nozA15d、nozA25d之模擬結果 38 　　　　4-1-2　比較nozB5d、nozB15d、nozB25d之模擬結果 40 　　　　4-1-3　比較nozA與nozB之模擬結果 42 　　4-2　未受電磁力影響下，鑄模之流場及溫度場模擬結果 42 　　　　4-2-1　比較mA5d、mA15d、mA25d之模擬結果 43 　　　　4-2-2　比較mB5d、mB15d、mB25d之模擬結果 45 　　　　4-2-3　比較mA與mB之模擬結果 46 　　4-3　受電磁力影響下，鑄模之流場及溫度場模擬結果 47 　　　　4-3-1　mA5dz24、mA15dz24、mA25dz24之模擬結果比較 47 　　　　4-3-2　mB5dz24、mB15dz24、mB25dz24之模擬結果比較 49 　　　　4-3-3　比較mAz24與mBz24之模擬結果 51 　　4-4　改變電磁攪拌中心高度，鑄模之流場及溫度場模擬結果 51 　　　　4-4-1　mA25dz12、mA25dz24、mA25dz36之模擬結果比較 52 　　　　4-4-2　mB25dz12、mB25dz24、mB25dz36之模擬結果比較 53 　　　　4-4-3　比較mA25d與mB25d於不同電磁力高度之模擬結果 54 第五章　結論 56 符號說明 58 參考文獻 60 表目錄 Table 1 Simulation results for various port angle of nozA 65 Table 2 Simulation results for various port angle of nozB 66 Table 3 Geometric dimensions for various molds 67 Table 4 Simulation results for the impingement depths for various cases 68 Table 5 Simulation results at the meniscus for various cases 69 Table 6 Simulation results for F-factor for various cases 70 Table 7 Simulation results for K-factor for mA25d with different height of EMS 71 Table 8 Simulation results for K-factor for mB25d with different height of EMS 71 圖目錄 Fig. 1 Schematic diagram for the continuous casting process 73 Fig. 2 Schematic diagram of continuous casting with in-mold EMS 74 Fig. 3 Space 3D schematic diagram of the mold 75 Fig. 4 Space 3D schematic diagram of the mold around the ports 76 Fig. 5 Definition of L 76 Fig. 6 Distribution of L in the wide side direction for the 4-poles linear induction motor 77 Fig. 7 Distribution of EMF for 4-pole EMS 77 Fig. 8 Distribution of electromagnetic force at the XY plane in the central level of EMS 77 Fig. 9 Schematic diagram of in-mold electromagnetic stirring continuous casting apparatus 78 Fig. 10 Distribution of electromagnetic force at the XY plane in the central level of EMS 79 Fig. 11 Distribution of L factor along the x-direction at the central level of EMS 79 Fig. 12 Schematic diagram for electromagnetic force along the casting direction 80 Fig. 13 Definition of K 80 Fig. 14 Schematic diagram for the calculation of F-factor 81 Fig. 15 Flow compendium for using FIDAP 82 Fig. 16 Schematic diagrams for nozA 83 Fig. 17 Schematic diagrams for nozB 84 Fig. 18 Calculated velocity profile for nozA 85 Fig. 19 Calculated velocity profiles around the ports of nozA 86 Fig. 20 Calculated velocity profile for nozB 87 Fig. 21 Calculated velocity profiles around the ports of nozB 88 Fig. 22 Calculated velocity profiles at the symmetry plane y=0 for mA 89 Fig. 23 Calculated temperature profiles at the symmetry plane y=0 for mA 90 Fig. 24 Calculated velocity and temperature profiles at the meniscus for mA5d 91 Fig. 25 Calculated velocity and temperature profiles at the meniscus for mA15d 92 Fig. 26 Calculated velocity and temperature profiles at the meniscus for mA25d 93 Fig. 27 Level fluctuation at the meniscus for mA 94 Fig. 28 Calculated velocity profiles at the symmetry plane y=0 for mB 95 Fig. 29 Calculated temperature profiles at the symmetry plane y=0 for mB 96 Fig. 30 Calculated velocity and temperature profiles at the meniscus for mB5d 97 Fig. 31 Calculated velocity and temperature profiles at the meniscus for mB15d 98 Fig. 32 Calculated velocity and temperature profiles at the meniscus for mB25d 99 Fig. 33 Level fluctuation at the meniscus for mB 100 Fig. 34 Relationship between port jet angle and impingement depth in molds for mA and mB 101 Fig. 35 Section of affected EMF 102 Fig. 36 Calculated velocity profiles at the symmetry plane y=0 for mAz24 103 Fig. 37 Calculated temperature profiles at the symmetry plane y=0 for mAz24 104 Fig. 38 Calculated velocity and temperature profiles at the meniscus for mA5dz24 105 Fig. 39 Calculated velocity and temperature profiles at the meniscus for mA15dz24 106 Fig. 40 Calculated velocity and temperature profiles at the meniscus for mA25dz24 107 Fig. 41 Level fluctuation at the meniscus for mAz24 108 Fig. 42 Calculated velocity profiles at the symmetry plane y=0 for mBz24 109 Fig. 43 Calculated temperature profiles at the symmetry plane y=0 for mBz24 110 Fig. 44 Calculated velocity an temperature profiles at the meniscus for mB5dz24 111 Fig. 45 Calculated velocity an temperature profiles at the meniscus for mB15dz24 112 Fig. 46 Calculated velocity an temperature profiles at the meniscus for mB25dz24 113 Fig. 47 Level fluctuation at the meniscus for mBz24 114 Fig. 48 Calculated velocity profiles at the symmetry plane y=0 for mA25d with different height of EMS 115 Fig. 49 Calculated velocity profiles at the meniscus for mA25d with different height of EMS 116 Fig. 50 Level fluctuation at the meniscus for mA25d with different height of EMS 117 Fig. 51 Calculated velocity profiles at the symmetry plane y=0 for mB25d with different height of EMS 118 Fig. 52 Calculated velocity profiles at the meniscus for mA25d with different height of EMS 119 Fig. 53 Level fluctuation at the meniscus for mB25d with different height of EMS 120 Fig. 54 Relationship between F-factor and impingement depth in molds 1213038517 bytesapplication/pdfen-US電磁攪拌器連續鑄造扁鋼胚數值解析continuous castingin-mold electromagnetic stirring (MEMS)slabnumerical simulationthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/52145/1/ntu-96-R94524046-1.pdf