목차

I. Introduction 1
1. Introduction 2
1.1 Backgrounds 2
1.2 Literature survey 5
1.2.1 Suction recirculation and cavitation 5
1.2.2 Flow instability 7
1.2.3 Design optimization of turbomachinery 10
1.3 Motivation and objectives 12
1.4 Document structure 13
II. Methodology 15
2. Numerical Methods 16
2.1 Governing equations 16
2.1.1 Conservation equations 16
2.1.2 Reynolds-averaged Navier-Stokes equations 16
2.1.3 Shear-stress transport turbulence model 17
2.1.4 Multi-phase flow analysis 19
2.2 Numerical tool and scheme 20
2.3 Centrifugal pump models 20
2.4 Computational domain and boundary conditions 21
2.5 Computational grid systems 25
2.6 Convergence criteria and temporal resolution 27
2.7 Validation 28
2.8 Summary 32
3. Optimization Methodology 33
3.1 Problem formulation 33
3.2 Sensitivity analysis 34
3.3 Design of experiments 35
3.4 Surrogate Models 36
3.4.1 Kriging model 36
3.4.2 Response surface approximation model 36
3.5 Multi-objective genetic algorithm 37
3.6 K-means clustering 38
3.7 Summary 39
III. Suction Recirculation and Cavitation 40
4. Analysis and Design Optimization of Impeller to Reduce Suction Recirculation and Cavitation 41
4.1 Introduction 41
4.2 Geometric parameters 41
4.3 Objective functions 43
4.4 Results and discussion 45
4.4.1 Sensitivity analysis 45
4.4.2 Optimization results 46
4.4.3 Hydraulic performance 51
4.4.4 Internal flow analysis 53
4.5 Summary 56
5. Effects of Volute Cross-Sectional Area on Suction Recirculation and Cavitation 57
5.1 Introduction 57
5.2 Geometric parameters 57
5.3 Results and discussion 58
5.3.1 Hydraulic performance 58
5.3.2 Suction recirculation 59
5.3.3 Suction performance and cavitation 66
5.4 Summary 72
IV. Flow Instability 74
6. Relationship between Hydraulic Performance and Flow Instability 75
6.1 Introduction 75
6.2 Performance parameters 75
6.3 Results and discussion 76
6.3.1 Hydraulic performance 76
6.3.2 Flow instability inside volute 78
6.3.3 Flow instability inside impeller 83
6.3.4 Flow instability by interaction between impeller and volute 86
6.4 Summary 90
7. Design Optimization of Impeller and Volute to Improve Hydraulic Performance and Flow Stability 92
7.1 Introduction 92
7.2 Geometric parameters 92
7.3 Objective and constraint functions 93
7.4 Results and discussion 94
7.4.1 Sensitivity analysis 94
7.4.2 Multi-objective optimization 96
7.4.3 Hydraulic performance 99
7.4.4 Unsteady flow analysis 102
7.5 Summary 110
V. Conclusions 111
8. Conclusions 112
8.1 Concluding remarks 112
8.2 Suggestions for future work 113
References 116
Author’s Publications 125