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Effects of Flow Coefficient on Unsteady Impeller Loading : 유량 계수가 임펠러 비정상 하중에 미치는 영향
DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | 송성진 | - |
dc.contributor.author | 공동재 | - |
dc.date.accessioned | 2018-05-29T03:14:45Z | - |
dc.date.available | 2018-05-29T03:14:45Z | - |
dc.date.issued | 2018-02 | - |
dc.identifier.other | 000000149474 | - |
dc.identifier.uri | https://hdl.handle.net/10371/141383 | - |
dc.description | 학위논문 (석사)-- 서울대학교 대학원 : 공과대학 기계항공공학부, 2018. 2. 송성진. | - |
dc.description.abstract | Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulation has been conducted to investigate how flow coefficient affects unsteady impeller loading. Simulations have been carried out at three flow coefficients - near stall, design, and near choke conditions - for two radial gaps (1.04 and 1.10). For computational efficiency, the unsteady simulation has been conducted for two impeller and diffuser passages via Fourier Transformation method. Both steady and unsteady simulations have been validated against experimental data. For the radial gap of 1.04, the unsteady loading (the difference between the maximum and minimum loadings) is the largest at the near stall condition | - |
dc.description.abstract | second largest at the near choke condition | - |
dc.description.abstract | and smallest at the design condition. Flow coefficient effects on the unsteady impeller loading are mostly due to the variations in pressure fluctuations on the pressure side of the impeller blade. Relative to the design condition, the near stall condition shows lower minimum loading and the near choke condition shows higher maximum loading. Therefore, both off design conditions result in higher unsteady loading than the design condition. Such differences stem from the variations in the pitch-wise static pressure at the diffuser vane inlet caused by the flow incidence onto the diffuser vanes. For the radial gap of 1.10, unsteady impeller loading decreases at three flow coefficients compared to that of the radial gap of 1.04. In addition, flow coefficient has a negligible effect on the unsteady impeller loading. Such independence stems from the attenuated potential effect of the diffuser vane with the radial gap increase. | - |
dc.description.tableofcontents | Chapter 1. Introduction 1
1.1. Research Background 1 1.2. Previous Research 3 1.3. Research Motivation and Objectives 6 Chapter 2. Test Compressor 8 2.1. Geometry 8 2.2. Measurements 10 Chapter 3. Numerical Simulation 12 3.1. Grid 12 3.2. Numerical Methods 15 3.2.1. Steady Simulation 15 3.2.2. Unsteady Simulation 17 3.3. Numerical Method Validation 20 3.3.1. Grid Dependence Test 20 3.3.2. Compressor Map 21 3.3.3. Periodicity of Unsteady Simulation 23 3.3.4. Diffuser Vane Inlet Time Averaged Velocity Contour 25 3.3.5. Diffuser Vane Inlet Temporal Velocity Variation 27 Chapter 4. Results and Discussions 29 4.1. Radial gap of 1.04 29 4.1.1. Chord-wise Unsteady Loading Distribution 29 4.1.2. Origin of Unsteady Loading 32 4.1.3. Fast Fourier Transformation Analysis 38 4.1.4. Loading and Pressure Fluctuations 39 4.1.5. Diffuser Vane Inlet Pressure Distribution 44 4.2. Radial gap of 1.10 49 4.2.1. Chord-wise Unsteady Loading Distribution 49 4.2.2. Fast Fourier Transformation Analysis 52 4.2.3. Loading and Pressure Fluctuations 53 4.2.4. Diffuser Vane Inlet Pressure Distribution 57 Chapter 5. Conclusions 59 Bibliography 61 Abstract in Korean 64 | - |
dc.format | application/pdf | - |
dc.format.extent | 4275980 bytes | - |
dc.format.medium | application/pdf | - |
dc.language.iso | en | - |
dc.publisher | 서울대학교 대학원 | - |
dc.subject | Centrifugal compressor | - |
dc.subject | Flow coefficient | - |
dc.subject | Unsteady CFD | - |
dc.subject | Unsteady loading | - |
dc.subject.ddc | 621 | - |
dc.title | Effects of Flow Coefficient on Unsteady Impeller Loading | - |
dc.title.alternative | 유량 계수가 임펠러 비정상 하중에 미치는 영향 | - |
dc.type | Thesis | - |
dc.contributor.AlternativeAuthor | Dongjae Kong | - |
dc.description.degree | Master | - |
dc.contributor.affiliation | 공과대학 기계항공공학부 | - |
dc.date.awarded | 2018-02 | - |
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