KURENAI : Kyoto University Research Information Repository

f
h+ = op M
Jg
h a
Vr W • T
rm
+ vi-jg
vri - v
rco
Here vrc, is the terminal velocity of a single droplet. For the wake
regime it is given by [5,50]
1 (gop)21/3 v
rm=4D
u 99
In Table I, the maximum height of a droplet for the Stokes regime and
Newton's regime is also tabulated.
In Fig. 5, the maximum height calculated from Eq. (73) for vi/jg = 1,
vi/jg = 2, and vi/jg = 10 is plotted against the diameter ratio D/Dc where
Dc is the critical diameter having the terminal velocity equal to jg.
As mentioned above, the initial velocity of a droplet necessary to
rise more than height h is obtained as an inverse function of Eqs. (73) or
(74). It is a complicated function of D, jg, and h, therefore, the
analytical solution is not presented here. However, calculations based on
Eqs. (73) and (74) indicate that the effect of jg is not so strong for the
practical range of jg. From this observation, therefore, vh(D,jg,h) may
be approximated by the following simple expression for the range of jg
corresponding to bubbly or churn turbulent flow.
vh = 0
vh
(D < Dc)
=J2gh------pp
(D > Dc)
275
(75)
(76)
(77)
(78)
(79)