Note: Descriptions are shown in the official language in which they were submitted.
" ~0~3Z094
This invention relates to heat-power engineering and
has particular reference to atomizing device; the invention finds
appiication in those industries where quality atomization and/or
mixture-formation of various materials is involved, which may be
the case in firing systems, diverse chemical-engineering apparatus
and the like.
One prior-art atomizing device (cf., e.g. British
Patent No. 1,210,699 Cl.B2F~comprises a cylindrical swirl chamber
with a cylindrical nozzle maintained coaxially thereto, said
nozzle having a length much greater than its diameter. A small
chamfer-like widening of the nozzle is provided at the nozzle
exit. A pipe feeding the material to be atomized runs through
the swirl chamber and the nozzle respectively, the outlet pipe
ena having a plurality of through holes which may be situated
only within said chamf~er, while the outside end face of the pipe
outlet end is fiush with the nozzle exit end.
An atomizing gas is fed into the cylindrical swirl
chamber tangentially to the surface thereof, with the result
that said gas is given a rotary motion. While passing length-
wise along the axis of the device the atomizing gas passes intothe nozzle and from thence into the adjacent space of a corres-
ponding apparatus. When the a~omizing gas passes from the swirl
chamber into the nozzle, its degree of swirling -
'
-2
: - - - , - - - - : , :
.
1~)8Z094
is greatly increased due to the nozzle diameter being much less
than the swirl chamber diameter, to such an extent that acoustic
oscillations are set up in the nozzle. Upon feeding the material
being atomized inside the chamfer of the nozzle end, said
oscillations promote its finer atomization and further, after
the mixture has left the nozzle, to higher-quality rnixture forming.
However, only in a specific particular embodiment of
the device and at given particular rates of flow of the atomizing
gas, when the size of the device is selected within an optimum
ratio, a maximum power of acoustic oscillations emitted is
attained which cannot be provided in the device under consideration
owing to some particular feature of gasodynamic phenomena proceed-
ing therein. Furthermore, provision of the pipe outlet end
flush with the nozzle exit end adversely affects aerodynamic
conditions of the gas flow through the nozz~e annular ~ap which
results in further losses of energy given to the material being
atomized to make said material pass through said annular gap,
and reduces the amount of the energy of acoustic oscillations
generated in the nozzle.
It is therefore a general object of the present
invention to obviate the disadvantages mentioned above.
It is a specific object of the present invention to
provide such a construction of an atomizing device that would
~ ' ' - " -
1C)82094
enable one to considerably increase the power of the generated
acoustic oscillations of the flow of atomizing gas.
Said object is accomplished due to the fact that an
atomizing device, comprising a cylindrical swirl chamber, wherein
rotation of the flow of an atomizing gas occurs, said swirl
chamber having a nozzle to provide a higher degree of swirling
resulting in generation of acoustic oscillations, and a pipe
coaxially running through the chamber and the nozzle into the
zone of atomizing of the material fed therethrough, according to
the invention is provided with a second chamber which i5 a reson-
ator of acoustic oscillations corresponding to those of a swirled
flow of the atomizing gas, said chamber with its inlet hole
adjoining the nozzle end, while the outlet pipe end extends
substantially outwards of the nozzle to enter through the inlet
hole inside said second chamber, wherein atomization of the feed
material occurs.
Such an embodiment of the construction of the present
atomizing device enables one to considerably increase the power
of the generated acoustic oscillations of the flow of atomizing
gas.
The second chamber is desirably a quarter-wave
acoustic resonator.
The above~eature provides for o~timum conditionsof am~lifvinq~ --
the acoustic oscillations of the respective harmonics.
,
1082094
The second chamber is suitably a cylinder whose diameter
is a few times that of the nozzle.
This enables one to bring hydrodynamic and acoustic
characteristics of the second chamber in accord with those of
the nozzle, wherein acoustic oscillations are generated.
The length of the second chamber is suitably equal to
or greater than the diameter thereof.
This makes it possible to attain a simultaneous
maximum concentration of acoustic energy in one direction and
maximum ampiification thereof.
In addition, the outlet pipe end suitably has a plural-
ity of through holes and/or be provided with a spray spout.
This is conducive to a higher-quality atomization of
the material discharged from the pipe and better mixture forming,
accordingly.
In what follows the present invention is illustrated in
some specific embodiments thereof given with reference to the
accompanying drawings, wherein:
FIG. 1 is a schematic longitudinal sectionalview of an
atomizing device, according to one embodiment of the invention;
FIG. 2 is a schemat~~c cross-sectional view of the swirl
chamber in a specific embodiment of the present invention
featuring a tangentia~ feed of the atomizing gas, according to
the invention; and
~.
~ 30
.
.
~ ' ; : ` ' ' .
108Z094
FIG. 3 is a schematic view of a part of the second
chamber along with the outlet end of the pipe coaxially running
through the swirl chamber and the nozzle, in the case where
the outlet pipe end is provided with a spray spout, according
to the invention.
Reference to the accompanying drawings, the atomizing
device comprises a cylindrical swirl chamber 1 (FIG. 1) adapted
to cause the flow of an atomizing gas to rotate, said chamber
having a nozzle 2 adapted to enhance the degree of swirling
said gas resulting in the generation of acoustic oscillations.
A second chamber 3 adjoins the nozzle 2, for the oscillations
generated in the nozzle 2 to amplify. A pipe 4 is arranged
concentrically with the swirl chamber 1, the nozzle 2 and the
second chamber 3, said pipe being adaoted for the material being
atomized to feed to the point of its admission to the second
chamber 3.
An inside surface 5 of the swirl chamber 1 is cylindri-
cal-shaped so as to provide optimum conditions for causing rotation
of the flow of the atomizing gas. The shape of the surface 5
of the swirl chamber 1 may be arbitrary to suit additional re-
quirements imposed upon the device. The swirl chamber 1 communi-
cates with the nozzle 2 through an opening 6. The places of
transition from the swirl chamber 1 to the nozzle 2 are desirably
rounded off to reduce hydrodynamic losses. The transition from
the inside cylindrical surface 5
'
108Z094
of the swirl chamber ~ to the nozzle 2 ma~ be made curviline-
ar with a view to reducing hydrodynamic losses and improving
the hydrodynamic flow conditions of the swirled flow of the
atomizing gas. ~he nozzle 2 has an end 7.
~ ~ An inside surface 8 of the nozzle 2 is cylindrical-sha-
3~ i ped and is coaxial ~e the swirl chamber 1. ~ength ~1 of the
~ozzle 2 must be e~ual to about 0.7 to 5.0 of height ~2 f
the swirl chamber 1. With said dimensional requirements satis-
fied an optimum acoustical coupling between the interior spa-
ces of tha swirl chamber 1 and the nozzle 2 is achieved. In
addition, with the abovesaid length ~1 of the nozzle 2 a
stable s~irled flow of the atomizing gas is established ~hich
promotes the generation of stable acoustic oscillations. The
diameter D2 of the ~ozzle 2 is selected to be i~ a strict
relationship with the diameters I1 of the swirl chamber 1
~nd the diameter D3 of the inlet tangential sleeve 9 whenever
a tangential (with respeot to the inside cylindrical surface
5) admission of the atomizing gas is effected through the
tangential sleeve 9 (~IG. 2). ~his relationship is termed
the geometrical characteristic o~ a~ atomizing device and -
proves to be a dimensionless quantit~ expressed in a mathema-
tical ~unctiou A = ~
ris
where A is the geometricsl characteristic of the atomi-
zing device;
.. . ~ .
,.. .
. - :
- ~ ~
- .
- ' ' '
`` ~08Z094
R is the radius of the swirl chamber 1, (R = Dl );
rn is the radius of the nozzle 2 (rn= D2 );
riS is the cross-sectional radius of the inlet sleeve
9 (r = D
lS 2
The numerical value of the geometrical characteristic
A is selected so as to obtain optimum operating conditions there-
of. It is established experimentally that when generating
acoustic oscillations at a frequency of, say, 3.0 to 6.0 kHz,
the geometrical characteristic A of the atomizing device should
be within about 27 to 32 to obtain a maximum power of said
oscillations. ;
An inside surface 10 of the second chamber 3 is similar-
ly shaped as a cylinder to obtain its optimum hydrodynamic
characteristics. A surface 11 of the second chamber 3 (as
shown in FIG. 1~ is shaped as a parabola, though it may be shaped
as a plane or cone. The second chamber 3 has an inlet hole 12.
The second chamber 3 is adapted for amplifying the
acoustic oscillations generated in the nozzle 2, using the
resonation principle. The second chamber 3 is thus, in effect,
- a resonator, and its being connected, through the inlet hole 12
thereof, to the end 7 of the nozzle 2 results in an abrupt
amplification of the acoustic oscillations (by about 25 to 30
per cent). This owes its onset to the presen-
.. ....
- -- , ~ . : .
108Z094
ce o~ a resonance o~ the natural Dscillation ~requency of
the cavity of the second chambar 3 and the frequency of one
of the harmonics of acoustic oscillations emi'~ted i~ the
nozzle 2. In this respect the dimensions of the second cham-
ber 3 are to be selected so as to gain a specific acoustic
oscillation harmo~ic emitted by the nozzle 2. Thus, the se-
cond chamber 3 is essentially a third acoustic cavity a~ter
the swirl chamber 1 and the nozzle 2. At a de~inite rate
of ~low of the atomizing gas and an invariable spatial dimen-
sions of the device, the base ~requenc~of the emitted acous-
tic oscillations prove B to be definite. Accordingly, the di-
mensions o~ the second chamber 3 are strictly definite. ~he
length ~3 of the second chamber 3 o~ the acoustic resonator
is calculated b~ the known ~ormula f = a
where f is the resonant frequency of acou6tic oscilla-
tions; -
a is the sound velocity in the swirled outflow of
the atomizing gas;
L3 is the length of the second chamber 3 which is
a resonant ¢avity of acoustic oscillations.
~ he diameter D4 of the second chamber 3 is to be selec-
ted to suit the desired angle of flare of the spray at the
e~it o~ the nozzle 2 and proceedi~g ~rom the axial velocity
_9_
.
.. : . -
.
, . .' - ~ ~ . ` - -
. . . ... .. . . . . . .
~ .. .. . . . . . .
108Z094
o~ the swirled ~low of gas, i.e., the flow rate thereof
At s~all angles of ~lare the diameter D4 of the second cham-
ber ~ is small, and vice versa.
Nlaximum amplification of acoustic oscillations by the --
second chamber 3 occurs when the ratio between the diameter
D4 thereo~ and the diameter D2 of the nozzle 2 equals approxi
mately 1.2 to 4.5.
Inasmuch as the second chamber 3 is an acoustic resona-
~or it must meet all requirements i~posed upon resonant acous~
tic cavities. ~hus, e.g., its length L3 may be divisible by
one-~ourth of the wavelength of acoustic oscillations of
the swirled ~low of the atomizing gas, i.e., the second cham-
~ber 3 may serve as a quarter-wave reso~ator. In additio~, it
must satisfy the following prerequisite: its length ~3 must ~-
be equal to or in excess of the diameter D4 thereof. The
admission end of the pipe 4 is communicated with a pipe 14
feedi~g the material to be atomized thereto through a hole
13. A sur~ace 15 of the pipe 4 is cylindrical throughout
its entire length. ~he pipes 4 and 14 are in~erco~nected
through a bushing 16 servi~g for a conce~tric arrangement
of the pipe 4 inside the swirl chamber 1, the nozzle 2 and th~
second chamber ~. Apart ~rom that, an outside sur~ace 17 o~
the bushing 16 is prov~ded with helical grooves 18 for the
atomizing gas to ~eed ~rom a pipe 19 into the swirl chamber 1,
-
~ ., ., ., . . . , - , , , ~; . . .
. .. . .... .. . - . .. .. .... .. .. . .
. , ., . - . . .. . . . - . -
: - . . . . - , . . .
.: . . .- - - . - ... . ..
. . . - .
- . - ,- . - . . .
.
108Z094
at the same time rotating the ~low of gas with a view to ef-
fecting a tan~entional admission of said atomizing gas into
the swirl chamber 1.
The outlet portion of the pipe 4 is closed at the exit
end thereof by a blank plug 20 ~hich is taper-shaped in the
given particular embodiment of the device, said blank plug
20 having a number o~ holes 21 for the material to be atomi-
zed to discharge. ~he cylindrical surface 15 of the outlet
portion o~ the pipe 4 also has a number o~ through holes 22
for the atomized material to discharge. The discharge holes
22 may be arranged in several rows. Apart from the discharge
holes 21 and 22 the outlet portio~ o~ the pipe 4 may be provi
ded with a spray spout 23 as illustrated in ~IG. 3 with an
outlet cone 24 ~eaturing a flare angle o~ about 20 to 160
and a helical insert 25 for the atomized material to rotate.
Variation of the distance ~4 from the axis of the holes 22 to
the e~it section of the second chamber 3 changes the quality
of atomization and operational reliability o~ the device a~d
mixture-~ormation. ~he best operating conditions of the
~evice as a ~hole is attained when the outside diameter ~5
of the pipe 4 equals 0.30 to 0.85 of the inside diameter D2
of the nozzle 2.
~ he material to be atomized is ~ed in the direction indi
cated by the arro~ A to get i~to the pipe 14, said pipe ~4
having the diameter D6 large enough to reduce its hydrody~a-
-'11-
!V `
:,~.. . . ,,,, .. , . . ., ,'' :
''' ',' . '' '~'.' ''- ' ' '. ', ' :' ': '
- : ' ' . - :
', ' " .,'- :
.
108Z094
mic resistance. ~rom the pipe 14 the material passes into
the pipe 4 through the holc 13 to flow along said pipe to the
discharge holes 2~ and 22 through which it is fed into the
second chamber 3 in a number of fine streams. ~Jhen the materi
al being atomized flows out from the d~charge holes 21 and 22
it becomes preatomized in the flow o~ atomizing gas due to
said flow expanding while passing through the second chamber
3. ~he atomizing gas is fed in the direction indicated by
the arrows B to the pipe 19 having a diameter D7 large enough
to reduce hydrodynamic losses therein. ~rom the pipe 19 the
atomizing gas gets into the helical grooves 18, wherein it
is i~parted rotation and is then admitted tangentially to the
swirl chamber ~. It is in the swirl chamber 1 ~hat the ~low
conditions of t~e atomizing gas becomes stabilized. ~rom the
swirl chamber 1 the rotated flow of the atomizing gas is di-
rected to the ~ozzle 2, where its rotational velocity is gre-
atly increased to such an amount that acoustic oscillations
set up in the nozzle 2. Said oscillations owe their origin
to an intexaction of the swirled flow of the atomizing gas
flowing ou-t from th~ nozzle 2 and the back flow of the surrou
nding atmosphere getting into the nozzle 2, i.e., to a ver~
high rarefaction established at the exit of the nozzle 2. It
shall b~ noted that a rarefaction, though o~ much less extent
has been provided in the swirl chamber 1 as well. ~hen the
acoustically e~cited flow of the atomiziug gas is fed from
.` - '.
-12-
.:
. . . . , . - .
:- - . , . ~ . :
. . , ~ . .
. . . - .. . . .
. , . . - .
. : . - .
: . ' '
~08Z094
the nozzle 2 to the second chamber 3, wherein the natural
oscillation f~equency equals that of acoustic oscillations of
the swirled ~low of t~e atomizing gas. It is in said chamber
that the ~low ~f the atomizing gas is turned to get forced
against the inside surface thereof, thus ~lowi~g around said
surface while moving about the axis of the second chamber 3
and lengthwise said axis. Thus, the provision of the abovemen
tioned gasdynamic phenomena makes it possible to amplify the
acoustic oscillations of the rotating flow of the atomizing
gas due to the presence of t~e followi~g effects. ~irst, am-
plification of acoustic oscillations occurs in the second
chamber 3 due to a resonance between the frequency o~ acous-
tic oscillations of the swirled flow of the atomizing gas and
the frequency of the natural oscillatio~s of the second cham-
ber 3. Secondly9 the conditions of reflection and interferen-
ce of acoustic waves provided in the second chamber 3 enable
said waves to be amplified and, moreover,, concentrated in a
single direction. Furthermore, amplification of acoustic
oscillations is affected by the interaction of the swirled
flow o~ the atomizing gas flowing out ~rom the second chamber
3 with the ~low of the atmosphere surrounding the atomizing
de~ice, maki~g its wa~ into the second chamber 3.
- ~he flow of the atomizi~g gas fiwirled i~side the second
chamber 3 with the amplfied acoustic oscillations therei~
-13-
- -. : - - .. .. -- ~ - ~, - - -
. - ~ , . ~, . -
' ' ' ' :' ' . :''
,~
-
::
:: . . :
1082094
ac~s upon the streams of the material being atomized flowin~
out from the discharge holes 21 and 22 of the outlet portion
of the pipe 4 to atomize said streams. The atomizing effect
is intensified also due to the fact that t~e rotating acous-
tically excited flow of the atomizing gas acts upon the
streams o~ the material being handled just at the instance
said streams are no longer a solid medium but are i~ fact a
stream of separate particles, i.e.~ lurther disintegration
thereo~ takes place. This i8 conduced by the spatial dimensi-
ons o~ the second chamber 3 which enable one to provide the
distance long enough ~or th~ streams of the material to preat
omize when said streams pass from the holes 22 to the surface
10 of the second chamber 3. Provision of a definite and long
enough distance ~4 between the streams flowing out ~rom the
holes 21 and 22, and the e~it section o~ the second chamber
3 establishes a condition for a quality preliminary mixture
formation ~eaturing high ~ineness ratio of the particles
thereo~ a~d their evan spread across the spray area. All
this what is just needed for utilization o~ the gi~en atomi-
zing device i~ those process appsratus where quality disper-
sion and mi~ture ~ormation is required. -
It i8 a quality dispersing and mixture forming that is
necessary, say, i~ ~uel combustion process occurring in bur-
ner de~ices. ~here~ore, the given atomizing de~ice may be
-14-
.
~.................................. . . . . .
' ~. . '
~- .
.
... . . . .
, : :
. . . - ,.
108;~094
applied in diverse burner devices, preferably in those fired
by liquid or gaseous fuels.
In such devices fuel and oxidant are fed into the ~iring
chamb~r as a preliminary prepared mixture, as preliminary
mixi~g proves to be one of the most e~ficien~ ways of inten-
sifying the combustion process.
~ he herein-proposed atomizing device, according to the
invention is advantageous i~ that acoustic energy concentra-
ted along the axis thereo~ makes it possible not only define
a quality mixture ~ormation but also establish a mLxture
spray discharged from the device, of the required shape.
Moreover, a secondary air stream flowing around the
device from out~ide, co~tributes to more efficient combustion
due to formation of fuel mixtures required for a complete
~uel combustion, and providi~g an additio~al combustion front
Apart from that effect, the secondary air stream additi-
onally cools the atomizing device of the present i~vention,
whereby the device is applicable i~ high-temperature and cor-
rosive conditions of Yiring systems, such as those of chemi-
cal engineering apparatus.
-'15
-- . .. - ... . ., . . - . -
~ - . . . : .
.
.
-
-
:
