Froude numbers

Froude number Fr Indirect spin-spin coupling J AS,... 

The dimensionless quantities in brackets are, respectively, the reciprocal of the Froude number, the Euler number, and the reciprocal of the Reynolds number for the system. 

If a continuous source of vapor is available, Froude numbers between 0.31 and l.O will give trouble. The Froude number is defined as follows ... 

Reference 2 gives a case history for a 30-in. line at I3,000gpm, and the author has observed a plant example for a 6-in. line at I45gpm. Both had Froude numbers in the troublesome range and both caused big problems. 

Vertical downflow" (Froude number rules for avoiding trouble)... 

This chapter reviews the various types of impellers, die flow patterns generated by diese agitators, correlation of die dimensionless parameters (i.e., Reynolds number, Froude number, and Power number), scale-up of mixers, heat transfer coefficients of jacketed agitated vessels, and die time required for heating or cooling diese vessels. 

Rushton et al. [10] performed extensive measurements of the power requirements for geometrically similar systems and found that for baffled tanks, the Froude number plays no part in determining the power requirements, as vortices do not form in such systems. For unbaffled systems, the Froude number plays a part above N g of about... 

Between the nonbuoyant jet region and the plume region lies an intermediate region in which the flow changes from the former to the latter.The axial location of the beginning of this intermediate region depends primarily on the exit Froude number ... 

Using the relation between the Froude number and the Archimedes number, Atq = 1/F, the length of the linear jet zone, x, where the buoyancy forces are negligibly small can be calculated as follows ... 

In the set of conservation equations described earlier, the Reynolds number and the Froude number must be the same for the model and the prototype. Since most industrial operations involve turbulent flow for which the Reynolds number dependence is insignificant, part of the dynamic similarity criteria can be achieved simply by ensuring that the flow in the model is also turbulent. For processes involving hot gases (i.e., buoyancy driving forces), the Froude number similarit) yields the required prototype exhaust rate as follows. 

The ratio Ap/p can be replaced by AT/T. Ar relates the influence of velocity and temperature of a jet when discharged into an environment of a different temperature. In some instances the Froude number, Galileo number, or Grashof number may replace the Archimedes number. 

Figure 5-16. Factors in Froude number exponent, n. By permission, Rushton, J. H., ef a/. [18].

Related to vortexes formation, depth of vortex related to geometric similarity and equal Froude number. 

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