APPENDIX 3
NOTES ON ELECTROSTATIC PRECIPITATOR
By H. J. uiuiova
1.
Laws of Motion of Small Particles Subjected to a Porce
(a) A small particle subjected to a force 4g accelerated thrpugh the mecis
e particles of
in the surrounding space, the resulting motion through
the media results in a resistive force to the motion giwen by Stokes a3
R
®
(1)
kdv «a
Yor spheres k * 377. When the velocity through the medial
that the resistive force is equal to the accelerating f
acceleration will be sero resulting in a constant veloc
the terminal velocity.
()
is such
e, the
y terned
For a spherical particle in a gravitational field
,
.
1
P
3
mg;
ni 4783p
z
z TB >p
The terminal velocity will remilt when
PF =
Ror i 1rd Pp
8
317d vps
a @
(2)
ory © 18
(c) Tf the perticle acquires an eleetrical charge and is in
trical f4eld the force on the particle will be
F
=
an elec-
QE
The terminal velocity will then be
Qt
377 4
-
(a)
(3)
For particles of a size approaching the mean free path of air
molecuiss, a correction dus to Cunningham is required $ account
for the additional velocity caused by the particle acc
between impacts. This is given by
v * Yerokes Q + ky >»)
-77UNCLASSIFIED
erating
(h)
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