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Home >> Mixing
Guide >> Static
Mixing Guide >> Liquid
Dispersion >> Weber Number |
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Weber Number
Effect of Weber Number
The Weber number (We) is the most important variable in controlling the drop
size of the dispersed phase. The Weber number can be expressed in many ways
depending on available data and units. For our purposes the following equation
applies: -
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Where Q = Flow rate (m3/h)r = Density (kg/m3)s = Interfacial tension (dynes/cm)
D = Pipe Inside Diameter (mm) |
Where Q = Flow rate (US gpm)sg = Specific Gravitys = Interfacial tension (dynes/cm)
D = Pipe Inside Diameter (inch) |
In general the Weber number expresses the ratio between inertial forces
trying to disperse the phases, to the interfacial forces trying to keep them
distinct. At a given viscosity ratio, the drop size therefore decreases as the
Weber number increases.
Interfacial Tension
Interfacial tensions usually range from 20 to 70 dynes/cm
Increasing values of interfacial tension decreases the Weber number, and therefore increases the drop size. Fluids with lower interfacial tensions will therefore more readily produce smaller drop sizes.
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