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博碩士論文 etd-0715108-154457 詳細資訊
Title page for etd-0715108-154457
論文名稱
Title
非穩態馬里哥尼流對熔區變化之影響
The Influence of Unsteady Marangoni Flow on the Molten Pool Shape
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
43
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2008-07-02
繳交日期
Date of Submission
2008-07-15
關鍵字
Keywords
尺寸因次分析、熔池形狀、熱毛細對流
molten pool shape, scale analysis, thermocapillary convection
統計
Statistics
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The thesis/dissertation has been browsed 5646 times, has been downloaded 4 times.
中文摘要
本研究是利用數值預測焊接或熔化過程在與時間有關和高斯入射能量,在暫態二維的熱毛細對流對熔區形狀之影響。熔化區的強度、微結構和機械性質和熔池的形狀是密切相關的。在此研究裡,與時間有關的入射通量是受到焊接速度與入射能量參數的作用。在穩態的三維情況下,傳輸過程是以時間來切割找出最大熔區。在不同的Prandtl數與Marangoni數的自由表面下,對於焊接熔化過程熔池形狀劃分出不同的區域。Prandtl數與入射能量對於熔區的流場、溫度場與熔池形狀,具有相當的影響。本篇研究預測是經由對照自由表面最高峰速度與熔池寬度,再經由尺寸因次分析證實。
Abstract
The transient two-dimensional thermocapillary convection and molten pool shape in melting or welding with a time-dependent and distributed incident flux are numerically predicted in this study. Determination of the molten pool shapes is crucial, because of its close relationships with the strength, microstructure, and mechanical properties of the fusion zone. In the work, the time-dependent incident flux is assumed to be a function of scanning speed and energy distribution parameter. Transport processes at the time corresponding to the maximum cross section can be identical to those under steady three-dimensional condition. The computed flow patterns and molten pool shapes under the flat free surface exhibits distinct regions for different Marangoni and Prandtl numbers. The effects of Peclet number and beam power on flow and temperature fields and fusion zone shapes are also presented. The computed results are confirmed by comparing the predicted peak speed on the free surface and molten pool width with those obtained from scale analysis provided in the literature.
目次 Table of Contents
目 錄 頁次
中文摘要 Ⅰ
英文摘要 Ⅱ
謝誌 Ⅲ
目錄 Ⅳ
圖目錄 Ⅵ
符號說明 Ⅷ

第一章 緒論 1
1.1 前言 1
1.2 本文架構 .4

第二章 理論模型之假設與分析 5
2.1 系統模型與假設 5
2.2 尺寸無因次化分析 10
第三章 結果與討論 11
第四章 結論 27
參考文獻 30
參考文獻 References
參考文獻
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