• 作者： 洪儒珍; 李啟忠
• 作者服務機構： 美國阿拉巴馬大學機械及太空工程學系
• 中文摘要： 一般相對論將時間，空間及重力結合在一起，乃是科學定理中最少經測試証明的理論。重力探測B衛星經使用迴轉儀及望遠鏡將探測一般相對論兩項最精密的試驗。迴轉儀及望遠鏡之最佳控制及機械穩定需求近絕對零度的極低溫度。與極低溫度之保持及推進劑之有效使用，建議採取超導流體液態氦。利用超導液體之特性，將液態氦通過多孔性栓塞之吸熱氣化，產生壓力噴泉，可用於衛星之姿態控制及無阻抗衛星之運行。本文旨在研究原型重力探測B衛星推進液箱中，由於重力跳動在液態與氣態氦界面所引發擾動之流體動態特性。尤以此界面擾動引發大波幅搖動波之激發。此大波幅搖動波之動盪，進而引動非均勻性之大波幅流體應力加諸於衛星推進劑箱之牆壁。本研究可提供衛星姿態，動態控制設計所需之最佳自動控制之資料。並確保一般相對論測試所需，最精密而無阻抗衛星之最佳試驗背景。
• 英文摘要： The theory of general relativity, which weaves together space, time and gravitation, remains oneof the least tested scientific theories. The Gravity Probe-B (GP-B) Spacecraft will add two very exact newpositive tests of general relativity by facilitating instrumentation of gyroscopes and a telescope in whichnear zero temperature is required for control and mechanical stability of the instrument. The approachesto both cooling and control involve the use of superfluid liquid helium. Boil-off through a porous plug toproduce fountain pressure from the cryogenic liquid helium dewar will be used as a propellantto maintain attitude control and drag-free operation of the spacecraft. The dynamical behavior of fluids, in particular the effect of surface tension on partially-filledrotating fluids (cryogenic liquid helium and helium vapor) in a full scale GP-B Spacecraft propellant dewartank influenced by various frequencies of gravity jitters, has been investigated. Disturbances of fluid stressdistribution, caused by the excitation of slosh waves and their associated large amplitude disturbances onthe liquid-vapor interface, exerted on the outer and inner walls of the rotating dewar container also havebeen investigated. Results show that the disturbances of fluid stress distribution exerted on the outer andinner walls of the rotating dewar are closely related to the characteristics of slosh waves excited on theliquid-vapor interface in the rotating dewar tank. This can provide a set of tools for spacecraft dynamiccontrol, leading toward the control of spacecraft imbalance caused by uneven fluid stress distribution dueto slosh wave excitations.
• 中文關鍵字： spacecraft; micropgravity; cryogenic propellant; general relativity; propulsion system
• 英文關鍵字： --