Jet half-angle

Figure 19. Definition of jet penetration depth and jet half angle.

Jet Half Angle. Determination of jet half-angle is shown also in Fig. 19. The jet half-angle can thus be calculated from the experimentally measured bubble size and jet penetration depth as follows ... 

Experimentally observed jet half-angle range from 8° to 12° for the experimental data mentioned above. These compare to 10° suggested by Anagbo (1980) for a bubbling jet in liquid. 

The solids entrainment rate into a jet in a fluidized bed can be calculated from Eqs. (61) and (23) if the empirical constants C1 and C2 and the jet half-angle 6 are known. The jet half-angle 6 can be taken to be 10° as suggested by Anagbo (1980), a value very close to 7.5° obtained from solid particle trajectories reported here. The real jet half-angle will be larger than 7.5° because of the truncation of the jet by the front plate of the semicircular bed. 

The jets in fluidized beds have the following properties the jet penetration depth, the jet expansion angle (or the jet half angle), gas and solids entrainment, initial bubble size, and frequency issuing from the jets. They will be discussed now. 

Merry (1975) correlated the experimental jet half angle reported in the literature and suggested the equation -0.3... 

Based on the definition by Merry, the jet half angle can be calculated if the initial bubble size and the jet penetration depth are known. 

A recent study by Vaccaro (1997) indicated that the jet half angle could be correlated with the two-phase Froude number quite well for do/do > 7.5. 

For multiple-jet systems such as that above a gas distributor plate, Wu and Whiting (1988) suggested to make use of the jet half angle discussed earlier to derive an equation for jet penetration depth. Their proposed equation is... 

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