ISBN: 3540658874
TITLE: Dynamics of Droplets
AUTHOR: Frohn, Arnold; Roth, Norbert
TOC:

Preface V
1. Theory 1
1.1 Surface Tension and Internal Pressure 1
1.2 Liquid-Liquid and Solid-Liquid Interfaces 8
1.3 Charged Droplets 10
1.4 Small-Amplitude Droplet Oscillations 12
1.5 Internal Circulation 14
1.6 Instability of Droplets 15
1.7 Instability of Jets 15
1.8 Relaxation Phenomena 16
1.8.1 Relaxation of velocity 17
1.8.2 Relaxation of temperature 20
1.9 Thermodynamics 21
1.9.1 Multiphase Systems 21
1.9.2 Kelvin-Helmholtz Equation 24
1.9.3 Thermodynamics of the Interface 25
1.9.4 Gibbs Isotherm 28
1.10 Phase Transition Processes 29
1.11 Evaporation of a Single Droplet 29
1.11.1 Diffusion-controlled evaporation of a single droplet 32
1.11.2 Combustion of a single droplet 34
1.11.3 Evaporation of multicomponent droplets 37
1.11.4 Evaporation through films 38
1.11.5 Evaporation and combustion in droplet arrays 38
1.12 Interaction with Light 39
1.12.1 Geometrical approximation 40
1.12.2 Glare Points 42
1.12.3 Rainbow 44
1.12.4 Mie scattering 46
1.12.5 Influence of Gaussian Intensity Distribution 52
1.12.6 Radiation Pressure 57
1.12.7 Partial Wave Resonances 58
2. Droplet Generation 63
2.1 Introduction 63
2.2 Spray Generation 64
2.3 Droplet Stream Generator 65
2.3.1 Physical Principle and Technical Performance 65
2.3.2 Operation Characteristics 68
2.3.3 Operation Characteristics 68
2.4 Droplet on Demand Generator 80
2.5 Dropper 83
3. Droplet Systems 85
3.1 Introduction 85
3.2 Sprays 85
3.3 Droplet Streams 88
3.3.1 Monodisperse Streams 88
3.3.2 Droplet Arrays 91
3.3.3 Deflection with Electrical Field 92
3.4 Single Droplets 93
3.4.1 Single Moving Droplet 93
3.4.2 Aerodynamically Suspended Droplets 93
3.4.3 Droplet Suspension with Thin Fibers 93
3.4.4 Electrostatic Levitation 94
3.4.5 Electrodynamic Levitation 95
3.4.6 Electromagnetic Levitation 96
3.4.7 Dielectrophoretic Levitation 97
3.4.8 Ferrofuid Levitation 97
3.4.9 Optical Levitation 97
3.4.10 Acoustic Levitation 98
3.4.11 Microgravity experiments 102
3.4.12 Combined Levitation Techniques 102
4. Experimental and Measurement Techniques 105
4.1 Introduction 105
4.2 Photographic Observation Techniques 106
4.3 Droplet stroboscope 108
4.4 Video Observation Techniques 110
4.5 Velocity 112
4.5.1 Laser-Doppler Velocimetry 112
4.5.2 Laser-Two-Focus Velocimetry 113
4.5.3 Particle-Image Velocimetry 114
4.5.4 Young's fringes 115
4.6 Size 115
4.6.1 Images 115
4.6.2 Phase Doppler Technique 116
4.6.3 Interference Method 117
4.6.4 White-Light Method 119
4.6.5 Glare Point Method 119
4.6.6 Rainbow 120
4.6.7 Other Techniques 121
4.7 Refractive Index 123
4.7.1 Introducing Remarks 123
4.7.2 Phase Doppler Based Instruments 124
4.7.3 Glare points 125
4.7.4 Rainbow 125
4.8 Temperature 129
4.8.1 Thermocouples 129
4.8.2 Schlieren Method 129
4.8.3 Infrared Method 130
4.8.4 Thermochromic Liquid Crystals 130
4.8.5 Other Methods 130
4.9 Surface Tension 131
4.10 Size Change Rates 131
5. Experiments to Study Mechanical Interactions 135
5.1 Introduction 135
5.2 Droplet-Gas Interaction with surrounding fluids 135
5.2.1 Wind tunnels for the investigation of droplet systems 136
5.2.2 Interaction with Acoustic Field 140
5.2.3 Shock Tube Experiments 145
5.2.4 Droplet Deformation 147
5.2.5 Droplet Fragmentation by Shock Waves 147
5.2.6 Ignition Delay Times of Droplets in Shock Tubes 150
5.3 Droplet Interaction with Solid and Liquid Surfaces 151
5.3.1 Cold Solid Surfaces 152
5.3.2 Cold Liquid Surfaces 153
5.3.3 Heated Surfaces 153
5.3.4 Wetting of Solid Walls During Droplet Impact 168
5.3.5 Comparison with Numerical Results 173
5.4 Droplet-Droplet Interaction 178
5.4.1 The dynamics and geometry of a binary encounter 179
5.4.2 Experimental Setup and Results 180
5.4.3 Numerical Results for Binary Droplet Collisions 186
6. Experiments to Study Phase Transition Processes 191
6.1 Introduction 191
6.2 Experimental Setups 192
6.2.1 Arrangements and Sensors to Detect Scattered Light 192
6.2.2 Optically Levitated Droplets 194
6.2.3 Acoustically Levitated Droplets 197
6.2.4 Droplet Streams 198
6.3 Evaporation 200
6.3.1 Measurements on Single Droplets 200
6.3.2 Measurements on Droplet Streams 210
6.4 Combustion 214
6.4.1 Burning Rates 218
6.4.2 Droplet Temperature 222
6.4.3 Flame Propagation 223
6.4.4 Microexplosions 229
6.5 Freezing 232
6.5.1 Droplet Size and Shape 235
6.5.2 Depolarization 237
6.6 Droplet Streams in High Pressure Environments 240
7. Miscellaneous Applications 245
7.1 Introduction 245
7.2 Internal Combustion Engines 245
7.3 Fire Suppression 245
7.4 Spray Cooling 246
7.5 Fuel-Coolant Interaction in Nuclear Reactors 246
7.6 Cleaning with High Pressure Jets 246
7.7 Medicine and Health 246
7.8 Bioaerosols 247
7.9 Production of Small Solid Particles 248
7.10 Applications in Agriculture 248
7.11 Acid Rain 249
7.12 Cloud Physics 249
7.13 Air Traffic and Condensation Trails 250
7.14 Effects of Heavy Rain and Ice Accretion on Aircraft Wings 250
7.15 Applications in Space 251
7.16 Droplets in a Microgravity Environment 252
7.17 Droplets as Chemical Reactor 252
7.18 Atomization of Alloy Powders 252
7.19 Ink-Jet Printing 253
7.20 Solder Jet Technology 253
7.21 Picoliter Fluid Dispenser in Biotechnology 254
7.22 Micro-Jet Printing of Microlenses 254
7.23 Applications in Medicine 254
7.24 Droplet-Based Manufacturing 254
7.25 Thermal Spraying 256
7.26 Compound droplets 256
7.27 Microencapsulation 256
7.28 Submicron Particles and Microspheres 257
7.29 Slurry Droplets 257
7.30 Emulsions 258
7.31 Aerosols 258
7.32 Contact Angles and Wettability 259
7.33 Droplet Separation Technology 260
References 261
Index 289
END
