1070-4272/01/7412-2054 $25.00 C 2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 12, 2001, pp. 2054!2060. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 12, 2001,
Original Russian Text Copyright C 2001 by Protod’yakonova, Aniskin, Kadashevich.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Effect of Polydisperse Drop Composition on Hydrodynamics
of Gas-Fluid Jet
O. I. Protod’yakonova, S. V. Aniskin, and Yu. I. Kadashevich
St. Petersburg State Technical University of Plant Polymers, St. Petersburg, Russia
Received July 12, 2001
Abstract-A model is constructed describing the hydrodynamics of a polydisperse gas-fluid jet outflowing
from a single-plume atomizer in a spray scrubber. Results of a calculation of hydrodynamic characteristics of
a polydisperse plume, obtained using the proposed model, are presented and assessed.
Description of flowing gas-fluid jets in spray mass-
exchange apparatus is an essential component of mod-
els of adsorption processes carried out in these ap-
paratus. In a number of studies [1, 2], models of such
jets were constructed, assuming that drops in the gas-
fluid jet are monodisperse. However, it is known that
the amount of a component sorbed by absorber drop
strongly depends on the size of a drop and time of
its contact with the gas flow. Therefore, a model of
a mass-exchange process in the gas-fluid jet must take
into account the polydisperse drop-size composition.
Correspondingly, a model of a flowing gas-fluid jet,
which is an important component of the model of
a mass-exchange process, must take account of the
effect of the polydisperse drop composition on specific
features of the flow of a gas-fluid jet.
The aim of this study was to construct a model of
a flowing gas-fluid jet that would take into account
the effect of the polydisperse drop composition on
the jet dynamics. To solve this problem, we use as
a basis the previously developed hydrodynamic mod-
el of a free plume of atomized fluid  whose main
advantages over the known models consist in that
there is no necessity for determining preliminarily
the gas jet boundaries in calculating the flow and in
the possibility of taking into account the nonuniform
gas velocity distribution in the jet.
In this study, the model taking into account the
drop polidispersity is constructed for that region of
the gas-fluid jet in which the process of fluid flow
breakup into drops may be considered complete. In
constructing the model, we make the following as-
sumptions. There is no drop breakup or coagulation.
The jet flow is stationary. The distribution of all
parameters of the gas-fluid jet is axially symmetric.
There is no heat exchange in the dispersed system.
The stress in the gas jet developing within the plume
of dispersed fluid is negligible as compared with the
stresses created in this jet by the drop flow. The drops
are polydisperse and have spherical shape. The gas-
fluid jet is directed vertically downwards.
Equations describing the flow of a polydisperse
gas-fluid jet are derived using the following consid-
erations. We assume that the jet plume can be re-
presented as a certain combination of m interpene-
trating plumes, each constituted by drops of the same
size. Let us introduce in the space a cylindrical system
of coordinates j, Y, Z. In accordance with the assump-
tion that the plume is axially symmetric, we consider
in what follows that all flow parameters are indepen-
dent of the angle j.
Let us divide each of the above m plumes into n
cone jets in such a way that the fluid flow rate G
within each of these jets is constant. We also assume
that the fluid is uniformly distributed over the cross-
section of each so-defined jet. Thus, the following
conditions are satisfied:
= const, k = 1, 2, ..., n; j = 1, 2, ..., m; (1)
77 = const,
if dG G
where indices k and j are, respectively, the number of
fluid jet in spatial partitioning of the plume and the
number of fraction of drops with certain size; S is the
cross-sectional area of the jet.
The total number of jet in such partitioning of the
gas-fluid plume is given by the product mn. Appar-