Mean droplet size water velocity

Various correlations for mean droplet size generated by plain-jet, prefilming, and miscellaneous air-blast atomizers using air as atomization gas are listed in Tables 4.7, 4.8, 4.9, and 4.10, respectively. In these correlations, ALR is the mass flow rate ratio of air to liquid, ALR = mAlmL, Dp is the prefilmer diameter, Dh is the hydraulic mean diameter of air exit duct, vr is the kinematic viscosity ratio relative to water, a is the radial distance from cup lip, DL is the diameter of cup at lip, Up is the cup peripheral velocity, Ur is the air to liquid velocity ratio defined as U=UAIUp, Lw is the diameter of wetted periphery between air and liquid streams, Aa is the flow area of atomizing air stream, m is a power index, PA is the pressure of air, and B is a composite numerical factor. The important parameters influencing the mean droplet size include relative velocity between atomization air/gas and liquid, mass flow rate ratio of air to liquid, physical properties of liquid (viscosity, density, surface tension) and air (density), and atomizer geometry as described by nozzle diameter, prefilmer diameter, etc. 

Some quantitative studies1498115011 on droplet size distribution in water atomization of melts showed that the mean droplet size increases with metal flow rate and reduces with water flow rate, water velocity, or water pressure. From detailed experimental studies on the water atomization of steel, Grandzol and Tallmadge15011 observed that water velocity is a fundamental variable influencing the mean droplet size, and further, it is the velocity component normal to the molten metal stream Uw sin , rather than parallel to the metal stream, that governs the mean droplet size. This may be attributed to the hypothesis that water atomization is an impact and shattering process, while gas atomization is predominantly an aerodynamic shear process. 

Figure 16 shows the results when 20 pore volumes of an emulsion having a 3.1- xm mean droplet size is injected into an 1170-mD sand pack and is followed by several pore volumes of water (ii). After emulsion injection, a permeability reduction of about 50% is observed. With water injection, the effluent concentration drops to 0 after one pore volume, whereas the permeability is unaltered. For this dilute emulsion, the droplets are captured in the porous medium, and this capture leads to blocking of the flow paths. Figure 16 shows that once the droplets are captured, they do not re-enter the flow stream, velocity being constant. Soo and Radke (ii) proposed the following physical interpretation for the results of Figure 15. Initially oil droplets are preferentially captured in the small-size pores, and as injection proceeds, more and more of the small pores become blocked. This blockage leads to a flow diversion toward larger size pores, and the rate...

As mentioned above, the faster the rate of adsorption of surfactant molecules, the greater the effect of reducing the droplet size. However, with liquid jets there is an important factor that may enhance surfactant adsorption. Addition of surfactants reduce the surface velocity (which is generally lower than the mean velocity of flow of the jet) below that obtained with pure water. This results from surface... 

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