KURENAI : Kyoto University Research Information Repository

*
' As shown in Figs . 7 through 17, the entrainment
the third power of j9/h*, which is also predicted by
Eq. (95). In collaboration with these experimental
proportionality constant C, and exponents n2 and n3
determined. Then the final form of the correlation
the momentum controlled region is given by
amount increases with
the present model by
data, the
in Eq. (95) are
for the entrainment in
Efg(h,jg) = 5.417 x 106 jg3 h*-3 Nug5 D*1.25 (\0.31 oP (96)
Figure 19 shows the comparison of various data to the above
**
correlation in Efg/{Nug5 DH1.25vs. 0)-0.311 jg/hplane. As can be
seen from this comparison, Eq. (96) satisfactorily correlates the wide
range of experimental data for entrainment in the momentum controlled
region. Further comparisons of data to the correlation are shown in Figs.
7 through 18. This correlation applies to the intermediate gas flux
regime.
Figure 19 shows that at low values of j*g/h*, the dependence of the
entrainment on j*g/h* changes. This change is caused by the flow regime
transition in a liquid pool. As mentioned in Section V, when the gas
velocity is small, the flow regime becomes bubbly flow. The discrete
bubbles rise up to the pool interface and collapse there. This is
different from the mechanisms under which Eq. (96) is derived. In this
bubbly flow regime, the droplet size distribution and initial velocity
distribution may be quite different from those predicted by Eqs. (40) and
(65). This regime corresponds to the low gas flux regime previously
mentioned. Indeed, the change from the low to intermediate gas flux
regime occurs approximately atj9 predicted by Eq. (42) which is derived
from the criteria of flow regime transition from bubbly to churn turbulent
flow in a pool.
Although data are scarce and considerable scattering is observed, the
entrainment in the low gas flux regime may be correlated by
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