Spray Simulation: Modeling and Numerical Simulation of Sprayforming metals

Cover......Page 1
Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Preface......Page 9
Nomenclature......Page 12
Indices......Page 15
1 Introduction......Page 17
2.1 The spray forming process......Page 22
2.2 Division of spray forming into subprocesses......Page 26
2.2.1 Subdivision of process steps and interaction of components......Page 29
Physical model......Page 37
Numerical model......Page 39
Visualization......Page 41
4 Fluid disintegration......Page 42
4.1 Melt flow in tundish and nozzle......Page 44
4.1.1 Melt flow inside the nozzle......Page 45
4.1.2 Fluid jet......Page 51
Volume of fluid (VOF) method......Page 52
Simplification: homogeneous two-phase model......Page 53
Results for the fluid jet......Page 54
4.2 The gas flow field near the nozzle......Page 59
4.2.1 Subsonic flow field......Page 60
4.2.2 Supersonic flow......Page 68
Principle of underexpanded jets......Page 69
Principle of underexpanded interacting gas jet systems......Page 71
Numerical simulation of underexpanded jets......Page 72
Numerical simulation of individual jets and jet systems......Page 74
Comparison of different jet configurations......Page 76
Numerical simulation of gas flow near the nozzle of a free-fall atomizer (two-dimensional)......Page 78
Numerical simulation of gas flow near the nozzle of a twin-fluid atomizer (three-dimensional)......Page 81
4.3 Jet disintegration......Page 83
4.3.1 Stability analysis......Page 84
Large-wavelength area......Page 85
Small-wavelength area......Page 86
Free-fall atomizer......Page 91
Drop-size correlation......Page 94
Close-coupled atomizer......Page 96
General fragmentation modelling approaches......Page 99
Direct numerical analysis and simulation of phase boundary dynamics......Page 101
4.3.3 Secondary atomization......Page 103
Secondary break-up in spray forming applications......Page 105
5 Spray......Page 110
Eulerian/Lagrangian approach......Page 112
5.1 Particle movement and cooling......Page 113
5.1.1 Momentum transfer and particle trajectory equation......Page 114
Analysis of droplet behaviour on the centre-line of the spray (one-dimensional)......Page 117
Turbulent dispersion of particles in the spray......Page 121
5.1.2 Heat transfer and particle cooling......Page 123
Solidification model in spray forming......Page 125
Model results......Page 130
Solidification behaviour inside the melt particle......Page 135
5.2 Internal spray flow field......Page 137
Boundary conditions for the coupled approach......Page 139
Single-phase gas flow field......Page 140
Two-phase flow field......Page 141
Stochastic contribution to spray structure......Page 151
Thermal averaging of spray conditions......Page 153
Results of different thermal averaging methods......Page 155
5.3 Spray-chamber flow......Page 160
5.4 Droplet and particle collisions......Page 163
5.4.1 Collision between droplets/particles and other droplets/particles......Page 164
5.4.2 Collision of melt droplets with solid particles (ceramic)......Page 172
6.1 Droplet impact and compaction......Page 177
6.1.1 Drop deformation......Page 181
6.1.2 Droplet solidification during impact......Page 185
6.1.3 Secondary atomization during impact......Page 187
6.2 Geometric modelling......Page 192
6.2.1 Form-filling spray process......Page 196
6.2.2 Computer-hardware-tailored geometric simulation......Page 198
6.3.2 Assumptions......Page 203
6.3.3 Fundamental equation and coordinate transformation......Page 204
6.3.4 Boundary conditions......Page 207
6.3.5 Heat resistance coefficient......Page 208
6.3.6 Convective heat transfer across the surface of a spray formed billet......Page 212
6.3.7 Calculated model results for Gaussian deposit cooling......Page 216
6.3.8 Thermal simulation of billet geometry......Page 224
6.3.9 Modification of thermal boundary conditions......Page 229
6.4 Material properties......Page 234
6.4.2 Macro- and micopore formation......Page 235
6.4.3 Porosity model......Page 236
6.4.4 Microstructure modelling and material properties......Page 238
6.4.5 Grain-size modelling in spray forming......Page 241
6.4.6 Grain coarsening......Page 245
7 An integral modelling approach......Page 249
8 Summary and outlook......Page 259
Bibliography......Page 261
Spray forming......Page 285
Index......Page 287