English  |  正體中文  |  简体中文  |  全文筆數/總筆數 : 56999/90690 (63%)
造訪人次 : 12420561      線上人數 : 59
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library & TKU Library IR team.
搜尋範圍 查詢小技巧:
  • 您可在西文檢索詞彙前後加上"雙引號",以獲取較精準的檢索結果
  • 若欲以作者姓名搜尋,建議至進階搜尋限定作者欄位,可獲得較完整資料
  • 進階搜尋
    請使用永久網址來引用或連結此文件: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/45772


    題名: 稀薄氣體自由剪力層中動量相關函數之探討
    其他題名: The Momentum Fluctuation Correlations in Rarefied Free Shear Layer
    作者: 洪祖昌;Hong, Zuu-chang;傅維安;Fu, Wei-an;杜文謙;Duh, Wen-chien
    貢獻者: 淡江大學航空太空工程學系
    關鍵詞: 直接模擬蒙地卡羅法;稀薄氣體;自由剪力層;DSMC;Rarefied gas;Free shear layer
    日期: 1998-03
    上傳時間: 2013-03-20 16:21:02 (UTC+8)
    出版者: 臺南市:中國航空太空學會
    摘要: 本文係以直接模擬蒙地卡羅(Direct Simulation Monte Carlo, DSMC)法,計算兩種不同流速之平行流的首闊結構。自由流乃模擬距海平面109.75km高度下之大氣狀態:氧分率0.217,氮分率0.783,密度,溫度249(K),分子暈27.23(g/mol),自由徑0.649(m)。較大之自由流流速分別取爲12、16、20Mach而速度比爲0.3(即如8Mach與8*0.3Mach)及0.6。計算域則爲高自公尺(兩種流速之流體也左方邊界進入,各佔一半高度),長12公尺之矩形區域。分子模型探氧氮混合之雙原子分子模式。
    計算結果發現,混合區的成長(Mixing layer growth),與下游距離成線性關係;且在高超音速(Hypersonic flow)下及平行流同一速度比時,自由流馬赫數愈來高則混合區愈狹長。這些現象與連流高雷諾數平行流混合層類似。對混合區中速度、溫度、壓力、及密度的分佈情形亦加以分析討論。溫度與壓力在混合區中呈增加的趨勢,密度則在中心(core)部份呈減小,而在自由流與混合層交接附近呈增加的淚象。吾人更進一步探討自由剪力層中各階動量脈動相關函數(correlation functions of momentum fluctuations),等分佈情形,以初探在稀薄氣體自由混合層中物理量(動量)的“紊性”。動量傳遞中,由速度脈動所形成之傳遞量約爲分子黏滯性所形成之動量傳遞量的七成左右,此現象顯然比連性紊流中者爲低。
    The direct simulation of Monte Carlo method was employed to calculate the flow structures, such as mean velocities, temperatures, pressures and mean quantities of various order of momentum fluctuations correlations of a free shear layer at hypersonic speed. The free stream temperature was kept as 273 K for all cares of calculations. The free stream velocities (of the higher one stream) cons: dered were M(subscript ∞) 10.15 and 20. The free stream densities considered were 10^20, 10^21 and 10^22 per m^3. The velocity ratio chosen as r=0.3, 0.45 and 0.6 for the present calculations. From the comparisons of above mentioned conditions of the rarefied parallel flow structures it is found that the effect of the changes of free stream density on the various flow properties was monotonously as the length scale nondimensionalized by the mean free path of the free stream. For different M(subscript ∞) with the same velocity ratio r the calculated shear layer growth were almost the same for M(subscript ∞). The tendency of the distributions of various order of fluctuation correlations in the mixing layer was the same as that of the continuum one. The momentum transfer due to mean fluctation correlations was about 70% of that due to molecular viscosity. This is obviously lower that in the case of continuum shear layer
    關聯: 中國航空太空學會學刊=Transactions of the Aeronautical and Astronautical Society of the Republic of China 30(1),頁77-86
    顯示於類別:[航空太空工程學系暨研究所] 期刊論文
    [國際事務與戰略研究所] 專利

    文件中的檔案:

    檔案 大小格式瀏覽次數
    index.html0KbHTML226檢視/開啟

    在機構典藏中所有的資料項目都受到原著作權保護.

    TAIR相關文章

    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library & TKU Library IR teams. Copyright ©   - 回饋