Contents
1 Introduction to Complex Problems in Fluids Engineering 1
1.1 Background Knowledge 1
1.2 Strategies for Treating Complex Flows 2
1.2.1 Fundamental Flow Features 2
1.2.2 Common Methods for Treating Flow Issues 3
1.3 Characteristics of Flow Problems 5
1.3.1 Flow Quantities 5
1.3.2 Unsteadiness 5
1.3.3 Symmetry 6
1.3.4 Stability 6
1.3.5 Symmetry,Intermittency and Periodicity 7
1.3.6 Phase Change 7
1.3.7 Flows in an Integrated System 8
References 9
2 A Brief Overview of Research Methods 11
2.1 Introduction of Experiment 11
2.1.1 Definition of Experiment 11
2.1.2 Experimental Instruments 12
2.1.3 Fidelity of Experiment 14
2.2 Numerical Methods for Flows 14
2.2.1 Governing Equations 15
2.2.2 Turbulence Model 18
2.2.3 Turbulent Characteristics 19
2.2.4 Cavitation Model 21
2.2.5 Other Issues 22
2.3 Some Limitations of CFD 23
2.4 Structural Analysis 24
References 25
3 Submerged Waterjet 27
3.1 Fundamental Features of Submerged Waterjet 27
3.1.1 Experimental Set-Up 29
3.1.2 Average Flow Characteristics of Submerged Waterjet 31
3.1.3 Vorticity Distribution and Pressure Fluctuation 34
3.1.4 Cavitation 37
3.2 Submerged Waterjet Issued at Ultra-High Jet Pressures 41
3.2.1 Cavitation Erosion Mechanism 41
3.2.2 Experimental Methods and Rig 42
3.2.3 Results and Analysis 44
3.2.4 Summary 53
3.3 Cavitation Simulation for Submerged Waterjet and Experimental Validation 53
3.3.1 Numerical Model and Procedure 54
3.3.2 Discussion of Numerical Results 55
3.3.3 Cavitation Prediction 58
3.3.4 Experimental Setup 60
3.3.5 Experimental Results 61
3.4 Concluding Remarks 65
References 66
4 Motion of Bubble 71
4.1 Rising Bubble in Stationar} Water 71
4.1.1 Experimental Set-Up and Image-Processing Code 73
4.1.2 Experimental Results and Analysis 76
4.1.3 Summary 93
4.2 Bubbles Released in Horizontal Water Flow 93
4.2.1 Experimental Preparations 95
4.2.2 Results and Discussion 100
4.2.3 Bubble Deformation and Dimensionless Numbers 107
4.2.4 Summary 108
References 108
5 Wake Flow of the Ventilation Cylinder 113
5.1 Experimental Setup 113
5.1.1 Water Tunnel and Ventilated Cylinder 114
5.1.2 Optical Configuration 115
5.1.3 Bubbles Separation Algorithm 116
5.2 Velocity and Vorticity Distributions 117
5.3 Bubbles Size Prediction 119
5.3.1 Bubbly Flow Patterns 119
5.3.2 Bubble Size 120
5.3.3 Comparison of Bubble Size Distribution 123
5.4 Bubble Velocity Distribution 123
5.5 Statistical Features of Bubble Volume 124
5.6 Concluding Remarks 125
References 126
6 Drag-Type Hydraulic Rotor 129
6.1 Introduction 129
6.2 Experimental Setup 130
6.2.1 Drag-Type Hydraulic Rotor 130
6.2.2 Test Segment of the Water Tunnel 131
6.2.3 PIV Set-Up 132
6.3 Flow Patterns Near the Hydraulic Rotor 133
6.3.1 Wake Flow Patterns 133
6.3.2 Flow Characteristics Near the Rotor 138
6.3.3 Vorticity Distribution 140
6.4 Numerical Preparations 140
6.4.1 Governing Equations and Turbulence Model 140
6.4.2 Grid Deployment Scheme 143
6.4.3 Boundary Conditions 143
6.5 Validation of Numerical Simulation 144
6.6 Variation of Torque Coefficient with Rotor Rotation 145
References 148
7 Viscous Flows in the Impeller Pump 151
7.1 Introduction 151
7.2 Pump Structure and Parameters 153
7.3 Numerical Preparations 155
7.3.1 Governing Equations and Turbulence Model 155
7.3.2 Boundary Conditions 155
7.3.3 Verification of Numerical Settings 156
7.4 Results and Discussion 157
7.4.1 Pump Performance 157
7.4.2 Flow Patterns 158
7.4.3 Pressure Fluctuations 162
7.5 Hydraulic Forces Exerted on Impeller Blades 164
7.6 Concluding Remarks 166
References 168
8 Cavitation in the Condensate Pump 169
8.1 Introduction 169
8.2 Cavitation Feature of the Centrifugal Pump 170
8.3 Modification of Impeller Geometry 171
8.4 Pump Performance Experiment 172
8.5 Numerical Preparations 174
8.5.1 Governing Equations,Turbulence Model and Cavitation Model 174
8.5.2 Grid Deployment Scheme 174
8.5.3 Boundary Conditions 176
8.5.4 Validation of the Computational Scheme 176
8.6 Numerical Results and Discussion 177
8.6.1 Geometric Features of Cavitation 177
8.6.2 Effect of Flow Rate on Cavitation at NPSHa=3.0m 180
8.6.3 Effect of NPSHa on Cavitation at Design Flow Rate 183
8.7 Conclusions 186
References 187
9 Structural Aspect of the Impeller Pump 189
9.1 Flow-Structure Interaction in the Molten Salt Pump 189
9.1.1 A Brief Introduction of the Molten-Salt Pump 189
9.1.2 Numerical Set-Up for Flow Simulation 190
9.1.3 Flow Characteristics of the Pump 193
9.1.4 Numerical Setup for Structural Calculation 194
9.1.5 Temperature Distribution in the Rotor 195
9.1.6 Strength Analysis of the Rotor 196
9.1.7 Modal Analysis 199
9.1.8 Summary 202
9.2 Structural Improvement of a Condensate Pump 202
9.2.1 Overview of the Condensate Pump 202
9.2.2 Condensate Pump and Vibration Description 204
9.2.3 Flow Simulation for the Pump 206
9.2.4 Motor Test 211
9.2.5 Modal Analysis of the Original Pump Base 213
9.2.6 Improvement of Motor Supporting 216
References 222
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