- •Foreword
- •1. General Introduction
- •2. Processes and Techniques for Droplet Generation
- •2.1.0 Atomization of Normal Liquids
- •2.1.1 Pressure Jet Atomization
- •2.1.3 Fan Spray Atomization
- •2.1.4 Two-Fluid Atomization
- •2.1.5 Rotary Atomization
- •2.1.6 Effervescent Atomization
- •2.1.7 Electrostatic Atomization
- •2.1.8 Vibration Atomization
- •2.1.9 Whistle Atomization
- •2.1.10 Vaporization-Condensation Technique
- •2.1.11 Other Atomization Methods
- •2.2.0 Atomization of Melts
- •2.2.1 Gas Atomization
- •2.2.2 Water Atomization
- •2.2.3 Oil Atomization
- •2.2.4 Vacuum Atomization
- •2.2.5 Rotating Electrode Atomization
- •2.2.7 Electron Beam Rotating Disk Atomization
- •2.2.9 Centrifugal Shot Casting Atomization
- •2.2.10 Centrifugal Impact Atomization
- •2.2.11 Spinning Cup Atomization
- •2.2.12 Laser Spin Atomization
- •2.2.14 Vibrating Electrode Atomization
- •2.2.15 Ultrasonic Atomization
- •2.2.16 Steam Atomization
- •2.2.17 Other Atomization Methods
- •3.1.0 Droplet Formation
- •3.1.1 Droplet Formation in Atomization of Normal Liquids
- •3.1.2 Secondary Atomization
- •3.1.3 Droplet Formation in Atomization of Melts
- •3.2.0 Droplet Deformation on a Surface
- •3.2.3 Droplet Deformation and Solidification on a Cold Surface
- •3.2.4 Droplet Deformation and Evaporation on a Hot Surface
- •3.2.5 Interaction, Spreading and Splashing of Multiple Droplets on a Surface
- •3.2.6 Sessile Droplet Deformation on a Surface
- •3.2.7 Spreading and Splashing of Droplets into Shallow and Deep Pools
- •4.1.0 Concept and Definitions of Droplet Size Distribution
- •4.2.0 Correlations for Droplet Sizes of Normal Liquids
- •4.2.1 Pressure Jet Atomization
- •4.2.5 Rotary Atomization
- •4.2.6 Effervescent Atomization
- •4.2.7 Electrostatic Atomization
- •4.2.8 Ultrasonic Atomization
- •4.3.0 Correlations for Droplet Sizes of Melts
- •4.3.1 Gas Atomization
- •4.3.2 Water Atomization
- •4.3.3 Centrifugal Atomization
- •4.3.4 Solidification and Spheroidization
- •4.4.0 Correlations for Droplet Deformation Characteristics on a Surface
- •4.4.1 Viscous Dissipation Domain
- •4.4.2 Surface Tension Domain
- •4.4.3 Solidification Domain
- •4.4.4 Partial Solidification Prior to Impact
- •5.1.0 Energy Requirements and Efficiency
- •5.2.0 Modeling of Droplet Processes of Normal Liquids
- •5.2.1 Theoretical Analyses and Modeling of Liquid Jet and Sheet Breakup
- •5.2.2 Modeling of Droplet Formation, Breakup, Collision and Coalescence in Sprays
- •5.2.3 Theories and Analyses of Spray Structures and Flow Regimes
- •5.2.5 Modeling of Multiphase Flows and Heat and Mass Transfer in Sprays
- •5.3.0 Modeling of Droplet Processes of Melts
- •5.3.4 Modeling of Multiphase Flows and Heat Transfer in Sprays
- •5.4.0 Modeling of Droplet Deformation on a Surface
- •5.4.1 Modeling of Deformation of a Single Droplet on a Flat Surface
- •5.4.2 Modeling of Droplet Deformation and Solidification on a Cold Surface
- •6. Measurement Techniques for Droplet Properties and Intelligent Control of Droplet Processes
- •6.1.0 Measurement Techniques for Droplet Size
- •6.1.1 Mechanical Methods
- •6.1.2 Electrical Methods
- •6.1.3 Optical Methods
- •6.1.4 Other Methods
- •6.2.0 Measurement Techniques for Droplet Velocity
- •6.3.0 Measurement Techniques for Droplet Number Density
- •6.4.0 Measurement Techniques for Droplet Temperature
- •6.5.0 Measurement Techniques for Droplet Deformation on a Surface
- •6.6.0 Intelligent Control of Droplet Processes
- •Index
2
Processes and Techniques for Droplet Generation
Droplets can be generated by vapor condensation and deposi- tion,[33][36][53][54][70]-[72] atomization and spray,[1]-[5] or plasma spray of solid particles/wires.[42][43] Atomization is perhaps the most widely used process for droplet generation. Atomization generally refers to the disintegration of a bulk liquid material via an atomizer into droplets in a surrounding gas or vacuum with or without a spray chamber. An atomizer can be a nozzle (or an array of nozzles) that ejects the liquid and atomizing medium (gas or liquid), a centrifugal device, or an ultrasonic vibrator. Nozzles are utilized in atomizing liquids in many industrial and domestic applications. In atomization of melts, bulk liquids are formed typically by melting solid materials. The atomized droplets usually experience rapid cooling before solidified into the end-products, i.e., powders, patterned matrix of dots, net or near-net shape preforms, or surface coatings. Droplets can also be generated by melting solid particles (powders), wires, fibers or other shapes of solid materials. A notable example is plasma spray atomization.[49] In this process, solid particles are melted in a plasma flame and projected against a target surface to break up into droplets of about one fifth of the original sizes.
In this chapter, various processes and techniques for droplet generation are described in detail, along with their applications and associated materials systems.
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