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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/101433


    Title: 可壓縮液汽兩相流體算則在卡式座標格點的發展
    Other Titles: Development of Compressible Liquid and Vaopr Algorithms on Cartesian Grids
    Authors: 牛仰堯
    Contributors: 淡江大學航空太空工程學系
    Keywords: 冷凍劑之冷卻;空蝕流體;沉浸式邊界方法;兩相流;Helium Cryogenics;Multi-phase CFD;Cavitation;Immersed boundary Methods
    Date: 2012-08
    Issue Date: 2015-04-29 15:00:46 (UTC+8)
    Abstract: 近年來,在低溫、微重力以及太空載具對高效能冷卻系統的需求日益增加。而冷凍 劑之冷卻方法也廣泛的使用在液化氣廠與太空技術上。最有潛力而被看好的冷凍劑如液 態氦;具備有低溫下無黏滯性的特性視為極有效率也常被用於超導磁鐵、紅外線望遠鏡 以及其他工業應用的冷凍裝置。當液態氦用於冷卻時之空蝕現象常出現於管流並具備有 液氣兩種流體現象。此外 具有空蝕現象的導管 通常都用於控制火箭引擎內的液態燃料 與液態氧化劑的質量流率,因此探討液態氦冷凍劑的空蝕流體特性在流體力學來講是非 常有趣及重要的課題,也能提供新的工業上之應用。本計畫要延續2006年的先期工作去 發展一套均值兩相液氣的混合模式並提出一套考慮任意狀態方程式及新的估算黎曼解 算則。在我們所考慮的兩相流模式裡,我們假設動力與熱力的平衡,在此基礎上兩相及 之間的相變化均可以提出合理的假設與相關模式藉由可調式矩陣將所有的數值模式整 合成凝結氣化的全流域雙曲線的數值模式。本計畫為了能夠模擬複雜的外型 將加入沉 浸邊界法並應用在噴嘴與水下載具等工業應用上面。在數值模式發展中,空間離散將推 導新的黎曼解如近似 Roe 及 AUSM+up 型 通量分離法 配合MUSCL方程式以提高精度, 再以Implicit LU decomposition處理時間離散。本研究將 探討液體動力特性及液-汽 兩相界面及空蝕現象補捉,並進行一維兩相流體震波管及多維流場之驗證。 在此計畫分成二部分: 第一年 1. 發展純二維液體與可壓縮液氣兩相流體的程式並比較不同狀態方程式。 2. 採用較準確可信的狀態方程式 發展預調式二維沉浸式邊界可壓縮液體與液氣兩相 程式。 3. 發展適合二維液體與液氣沉浸式壓力及溫度之邊界條件。 4. 二維水下載具的模擬與管流及噴嘴的數值驗證。 第二年 1. 發展預調式純三維液體與液氣兩相流體的程式並考慮不同狀態方程式。 2. 採用較準確可信的狀態方程式 發展預調式三維沉浸式邊界可壓縮液體與液氣兩相 程式。 3. 發展平行預調式三維沉浸式邊界可壓縮液體與液氣兩相程式。 4. 發展適合三維液氣沉浸式壓力及溫度之邊界條件。 5. 三維水下載具的模擬與管流及噴嘴的數值驗證。
    Recently, the importance of the development of high performance cooling systems using cryogenic fluid refrigerant has markedly increased in liquefied gas plants and aerospace technology. Among such fluids, liquid helium is employed for cooling, cavitation frequently occurs in the flow duct, and the flow pattern consists of two phases. In addition, cavitating venturi is selected to control the liquid fuel and liquid oxidizer mass flow rates of a rocket engine development. Thus, investigation of the cavitating flow characteristics of cryogenic fluids such as liquid helium is very interesting and important not only in the basic study of the hydrodynamics of cryogenic fluids, but also for providing solutions to problems related to new practical engineering applications. This proposal is to continue our previous work (2006) on solving a locally homogeneous two-phase mixture for liquid-vapor flows. Here, a formulation for multi-phase flows with arbitrary equation of state based on the derived approximated Riemann solver is presented. In the two phase flow model, we consider a homogeneous two-phase mixture model with the assumption of kinematics and thermodynamics equilibriums. The thermodynamics behaviors of liquid phase, vapor phase and their phase transitional process are described by different equations of state which includes a mass-fraction averaged formula of liquid-vapor saturation process. The preconditioning strategy is utilized to reformulate the compressible mixture type Navier-Stokes equations coupling with a condensation-vaporization model to be hyperbolic at all-speed. The proposed approach is expected in the simulation of complicated underwater vehicle or nozzle and venturi flows. The immersed boundary method will be chosen to solve the proposed equations and model on Cartesian grids for the problems with complicated morphology. The proposal will be divided into two parts: 1st year: (1) To develop pure two-dimensional compressible liquid and liquid-vapor flow codes under different equations of state based on preconditioning. A more sophisticated preconditioning matrix and the related Riemann solvers are required to figure out to keep the numerical stability. (2) To develop two-dimensional an immersed boundary type compressible liquid and liquid-vapor flow codes with accurate equation of state based on preconditioning. (3) An enforced boundary condition to math realistic physics on solid surface such as temperature, velocity and pressure is required to work out for the two-phase flow model. (4) Numerical validation on nozzle and tube flows and underwater vehicle simulation. 2nd year 1. To develop three-dimensional liquid flow codes under different equations of state based on preconditioning 2. To develop an immersed three-dimensional boundary type liquid-vapor flow code。 3. To develop a parallelized three-dimensional immersed boundary type liquid-vapor flow 4. Numerical validation on nozzle and tube flows and underwater vehicle simulation.
    Appears in Collections:[航空太空工程學系暨研究所] 研究報告

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