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A numerical analysis of a correlation of swirl number in a coannular swirl injector : 동심환형 Swirl injector에서의 Swirl number에 대한 새로운 관계식의 제안 및 수치적 분석
DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | 도형록 | - |
dc.contributor.author | 최재훈 | - |
dc.date.accessioned | 2017-10-31T07:32:32Z | - |
dc.date.available | 2017-10-31T07:32:32Z | - |
dc.date.issued | 2017-08 | - |
dc.identifier.other | 000000146471 | - |
dc.identifier.uri | https://hdl.handle.net/10371/137334 | - |
dc.description | 학위논문 (석사)-- 서울대학교 대학원 공과대학 기계항공공학부, 2017. 8. 도형록. | - |
dc.description.abstract | Gas turbine combustors using lean-premixed combustion often utilizes
a swirling flow to generate a central-toiroidal recirculation zone (CTRZ) for flame stabilization. The characteristics of a CTRZ, such as the volume of a CTRZ, can be predicted by the swirl number at the combustor inlet (or the exit of the swirl injector). In the present study, a new numerical model for the swirl number is derived to estimate the swirl number at the end of a swirl-injector pipe, especially for the pipe with a variable cross-sectional area, where existing formulas cannot be applied accurately. First, a new one-dimensional model to predict the swirl decay rate is proposed to estimate the swirl intensity at the end of the swirl injector. Next, the proposed model is validated with the CFD simulations in various swirl injectors. As a result of validation, the proposed model is confirmed to be in good agreement with the results in CFD simulations. In Chapter 4, the variation of decay rate of swirl with the factors affecting the swirl is analyzed through the proposed model. It is found that the decay rate of swirl decreases as the inlet Reynolds number increases and initial swirl intensity decreases. It is also has been shown that a straight annular pipe can minimize the decay rate of swirl when having a specific the ratio of inner radius to outer radius of a swirl injector. This value is estimated as about $0.35$ according to the proposed model. It is expected that the proposed model of variation of swirl number is very useful for the selection of appropriate swirler to obtain the desired swirl number in swirl injectors. | - |
dc.description.tableofcontents | Chapter 1 Introduction 1
1.1 Motivation and objectives 1 1.2 Previous studies and background 5 Chapter 2 A new one-dimensional model for streamwise evolution of swirl number 9 2.1 Reynolds transport theorem (RTT) 11 2.2 Non-dimensionalization 15 2.3 Description of the tangential wall shear stresses 15 2.4 Verification of model for mean azimuthal velocity using a laminar flow 22 2.5 Description of the eddy viscosity 25 2.6 A new model for swirl number in turbulent flows 30 Chapter 3 Validation of the proposed model for the swirl number 34 3.1 Validation in a straight coannular swirl injector 35 3.2 Validation in a coannular swirl injector with variable cross-sectional area 38 3.3 Validation in a coannular swirl injector connected to a swirlstabilized burner 40 Chapter 4 Application of a new model 44 4.1 Selection of the proper swirler in a swirl-stabilized burner to produce the desired flow 44 4.2 Variation of swirl decay rate with the ratio of the inner radius to the outer radius in swirl injectors 47 4.3 Variation of swirl decay rate with inlet Reynolds number 49 4 4 Variation of swirl decay rate with the initial swirl intensity 50 Chapter 5 Conclusion 52 초록 60 | - |
dc.format | application/pdf | - |
dc.format.extent | 4555317 bytes | - |
dc.format.medium | application/pdf | - |
dc.language.iso | en | - |
dc.publisher | 서울대학교 대학원 | - |
dc.subject | Swirl number | - |
dc.subject | Decay rate of swirl | - |
dc.subject | Swirl injector | - |
dc.subject | Swirl-stabilized burner | - |
dc.subject.ddc | 621 | - |
dc.title | A numerical analysis of a correlation of swirl number in a coannular swirl injector | - |
dc.title.alternative | 동심환형 Swirl injector에서의 Swirl number에 대한 새로운 관계식의 제안 및 수치적 분석 | - |
dc.type | Thesis | - |
dc.contributor.AlternativeAuthor | Jaehoon Choi | - |
dc.description.degree | Master | - |
dc.contributor.affiliation | 공과대학 기계항공공학부 | - |
dc.date.awarded | 2017-08 | - |
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