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研究生:葉嵐凱
研究生(外文):L.K.Yeh
論文名稱:運用非線性紊流模式模擬受限渦旋流場
指導教授:林昭安
指導教授(外文):C.A.Lin
學位類別:碩士
校院名稱:國立清華大學
系所名稱:動力機械工程學系
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:2000
畢業學年度:88
語文別:英文
論文頁數:74
中文關鍵詞:非線性紊流模式
外文關鍵詞:non-linearturbulence model
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目前大部份使用的紊流模式主要為線性的EVM及REYNOLDS STRESS TRANSPORT MODEL,但由於所探討的流場結構日愈複雜線性EVM本身的數值缺點便無法準確模擬出流場特性,而REYNOLDS STRESS TRANSPORT MODEL雖較為準確,但求解過程較為複雜,計算時間較長,較不符經濟效益,因此近來便有些人發展出二階、三階非線性EVM,由每個研究者所發展出的模式在其所選定模擬的特定流場中確實比線性的EVM較為準確,但因每個模式是針對特定的流場與方法假設出不同的係數,因此是否適用於各種流場及其準確性與否便有待商確與探討,且到目前為止這些MODELS所模擬計算的流場並不多且較為簡單;因此目前工作是將不同非線性模式模擬於不同入口條件的較複雜渦漩流場並與實驗值加以比較與探討,並期能結合不同三階模式係數於更廣泛之流場計算與應用。

The present study focuses on simulating turbulent flows in a model coaxial combustor with and without swirl at the inlet by linear eddy viscosity model, non-linear eddy viscosity models, and explicit algebraic stress models. The numerical framework of the present predicting procedure is based on the finite volume method, adopting Hybrid and QUICK schemes in convective terms and SIMPLE algorithm to solve the pressure field.
There are three test cases considered in the present study. The first two are the coaxial dump combustor with and without swirl at the inlet. The third test case is a strongly swirling flow in a pipe with non-swirling central jet. The computations of non-swirling case indicate that the Craft et al.'s cubic model predicts the best results in terms of the mean and turbulent quantities compared to measurements. However, the Craft et al.'s cubic model did not deliver converging solution in the swirling cases. In the swirling case, which has a forced vortex inlet swirl profile, the explicit algebraic stress models perform better. The predictions of the strongly swirling flow show that explicit algebraic stress model is capable to capture the strong swirl and stress intensity with the swirl level being correctly predicted.

Contents
Abstract ……………………………………………………………… (i)
Nomenclature …………………………………………………………(iii)
List of Figures ………………………………………………………(vi)
List of Table ………………………………………………………(vii)
Contents ……………………………………………………………(viii)
Chapter 1 Introduction ………………………………………………1
1-1 Introduction ……………………………………………………1
1-2 Paper Survey ……………………………………………………2
1-3 Discussion of Turbulence Models ……………………………7
1-3-1 The Differential Models ……………………………………7
1-3-2 The Linear Eddy Viscosity Model …………………………8
1-3-3 The - Nonlinear Eddy Viscosity Model …………………9
1-3-4 The ASM and Explicit ASM …………………………………10
Chapter 2 Mathematical Formulations ……………………………12
2-1 Governing Equations ……………………………………………12
2-2 Turbulence Models ………………………………………………13
2-2-1 Linear Eddy Viscosity Model ……………………………13
2-2-2 Quadratic Non-linear Model ………………………………14
2-2-3 Explicit Algebraic Stress Model …………………………17
2-2-4 Cubic Non-linear Eddy Viscosity Model …………………18
Chapter 3 Numerical Solution Procedure ………………………20
3-1 Numerical Method of the Flow ………………………………20
3-2 Geometry and Boundary Conditions …………………………24
3-3 Solution Algorithm of the Flow ……………………………25
Chapter 4 Result and Discussion …………………………………27
4-1 Coaxial Dump Combustor Flows ………………………………28
4-1-1 Simple Dump …………………………………………………28
4-1-2 Forced Vortex ………………………………………………29
4-2 Strongly Swirling Flow ………………………………………30
Chapter 5 Conclusion ………………………………………………32
References ……………………………………………………………33

References
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