Note: Descriptions are shown in the official language in which they were submitted.
16
JOY 03030
FAN DIFFUSER AND COLLECTOR COMBINATION
FOR COOLING SYSTEMS IN DYNAMO ELECTRIC MACHINES
This invention relates generally to cooling
systems in gas cooled dynamo electric machines, and
particularly is a fan diffuser and collector
combination as part of the cooling system.
In dynamo electric machines, a great amount of
heat is venerated by the flow of currents through
the field and armature windings and by eddy current
heating in the stators core laminations. To protect
the integrity of the materials of the windings and
related supporting elements, a gas is utilized to
cool the various components in the machine. In large
dynamo electric machines, the field windings are part
of the rotor and the armature windings are port of
the stators The removal of heat from the various
components in the dynamo electric machine requires the
gas to be moved through many relatively small
passages in the rotor and the stators Patents issued
to Willing and Shartrand, US. Patent 3,348,081 and
3,139,208, respectively, disclose the passages
- 2 - JOY 3030
through the rotor and stators laminations as part of a
gas cooled dynamo electric machine
One method of circulating the gas through the
plurality of passages is accomplished by increasing the
static pressure or pressure head of the yes at a some
point in the cooling system. It is to be understood that
there are other methods of circulating the gas through
the cooling system of dynamoe]ectric machines however,
this invention is directed towards the method of
increasing the static pressure of the yes at a selected
point in the cooling system.
Generally, the cooling system of the dynamo--
electric machine will include some type of fan mechanism
at one or the other or both ends of the machine. The
fan is usually located on the rotor at that end. It
is to be understood that the detailed description
of the invention disclosed herein is directed to one
fan, at one end of the dynamo electric machine, and
associated with a cooling system. Since it is common
for dynamo electric machines to include two fans and
two interacting cooling systems at both ends of the
machine, the invention herein normally would be utilized
at both ends of the machine and in both cooling systems.
For ease of explanation, the description below relates to
only one cooling system which includes one fan at one
end of a machine.
The fan circulates the gas through the cooling
system by expelling the gas radially through an annular
chamber at one end of the dynamo electric machine. The
annular chamber is formed by an inner and an outer end
plate shield which are axially spaced apart and located
within the frame wrapper. Generally, the frame wrapper
surrounds both the stators and the rotor of the machine.
The gas passes through an arcuate port in the frame wrapper
towards a dome cooler, or means for cooling the gas, which is
I,
I:
JOY 03030
--3--
located atop the frame wrapper. Duct work from the
dome cooler to the passages in the frame wrapper
allow the gas to pass from the cooler and into the
stators laminations as described above.
In a reverse flow cooling system for a
dynamo electric machine, the gas flow is split at the
output of the dome cooler. A portion of the cooled
gas is directed into the stators and the remaining
portion of the gas is channeled through an annuls
duct work into the rotor passages. US. patent
number 3,739,208, issued to Shartrand, specifically
discloses this type of cooling system and
which Patent issued on June 12, 1973.
After the gas has been-introduced into the
stators passages and the rotor passages, and the gas
flows through both those elements, the gas eventually
enters the air gap between the stators and the rotor
and/or the interior space of the frame wrapper. The
circulation of the gas is completed by the fan
drawing the gas from the region of the stators and the
rotor and expelling the gas back into the annular
passage at one end of the dynamo electric machine.
Since the gas must pass through many passages
and be directed through and around the various
components of the dynamo electric machine, the primary
farce which circulates the gas through the machine is
the gas' pressure head or its static pressure head.
In other words, though the velocity of the gas may
contribute to some circulation throughout the
I machine, the gas is moved primarily by its static
pressure head. The gas which leaves the fan's
exhaust port has an initial static pressure head and
an initial velocity pressure head. The annular
chamber, which circumferential surrounds the
exhaust port of the fan, does no work on the gas that
flows through it. As is well known, Bernoulli's
theorem provides that if no work is done on or by an
incompressible fluid as it flows, the total head
- 21 1~4l6 JOY 03030
--4--
remains unchanged. In other words, if the velocity
head of the gas changes from one point in the cooling
system to another point when the pressure head of the
gas must change inversely to the change in the
velocity head of the gas. However, it should be
recognized that the heating-up or cooling down of the
gas is considered as work done on or by the gas,
hence eddy streams within the gas flow caused by
obstructions to the flow of gas may increase the
temperature of the gas and effect the transformation
of velocity head into static pressure head.
Although this theorem is relatively well known
in the art, the application of this principle to the
cooling systems of dynamo electric machines is not
easily accomplished. The annular chamber's axial
size, radial dimensions, and its orientation with
respect to the fan's exhaust and the other elements
of the dynamo electric machine severely limit the
application of Bernoulli's theorem. The orientation
of the annular chamber is affected by the end
windings which protrude axially towards the fan from
the stators of the machine, and the size of the
chamber is affected by the frame wrapper which
defines the radial extent of the machine, and by the
machine's bearings supporting the rotor.
In prior art devices, the annular chamber
primarily functioned as a passageway between the
exhaust port of the fan and an arcuate port through
the frame wrapper which leads to the intake duct for
the dome cooler. In some prior art devices, the
annular chamber his been a parallel walled passage
from the fan exhaust to the arcuate port. Although
these prior art devices do transform a portion of the
gas' velocity head into static pressure head by
virtue of the gas slowing down as it approaches the
radial extent of the annular chamber as defined by
the frame wrapper, the prior art devices have
ignored the eddy streams created in the gas flow by
the limited exit from the annular chamber through the
I ~14l6 JOY 03030
--5--
arcuate port in the frame wrapper and other
obstructions to the flow. These eddy streams cause
the gas to heat up, therefore, work is done on the
gas by the annular chamber in the form of changing
the thermal energy of the gas and the static pressure
head of the gas is not enhanced.
aye =
It is an object of this invention to provide for
a more efficient circulation of gas in the cooling
system of a gas cooled dynamo electric machine.
It is another object of this invention to
provide for a cooling system which includes means for
transforming a portion of the velocity head of the
gas into static pressure head.
It is an additional object of the present
invention to provide for a diffuser channel in the
inner radial portion of the annular chamber
immediately downstream of the exhaust port of the
fan.
It is a further object of the present invention
to provide an outer radial portion of the annular
chamber which collects the gas exiting the diffuser
channel and minimizes eddy streams in the gas as it
flows through the arcuate port in the frame wrapper.
It is another object of the present invention to
provide for a disk located in the inner radial
portion of the annular chamber which includes an
inboard surface and an outboard surface opposite the
inboard surface, wherein both surfaces of the disk
are spaced away from the inner and outer end plate
shields.
summary of the Invention
The present invention includes means for
transforming the velocity head of a gas expelled by a
fan, which is part of a cooling system for gas cooled
dynamo electric machine, into static pressure head.
In one embodiment of the invention, the fan is
located radially coextensive with an annular chamber
defined by an inner and an outer end plate shields
.6
JOY 03030
--6--
which are located at one end of the dynamo electric
machine. disk is disposed within the radially
inner portion of the annular chamber and has an
inboard surface which is substantially parallel to an
adjacent surface of one or tune shields. The inboard
surface and the adjacent surface define a diffuser
channel there between which receives all of the gas
expelled by the fan. The disk is foreshortened with
respect to the frame wrapper, hence the gas flows out
of the diffuser channel and into the outer radial
portion of the annular chamber. The disk includes an
outboard surface opposite the inboard surface which
is spaced away from the other shield. The gas
ultimately leaves the annular chamber through an
arcuate port in the frame wrapper and is channeled
through the intake duct of a cooling means located
atop the frame wrapper.
Brief Description of the Drawings
Figure 1 illustrates a partially cutaway view of
a dynamo electric machine which includes the disk
disposed in the annular chamber of the cooling system
of the machine;
Figure 2 illustrates a cooling system schematic
of a reverse flow, gas cooled, dynamo electric
machine;
Fissure 3 is a blow up of the left end portion or
Figure 2 which illustrates in detail a mixed flow
fan, and the diffuser channel and collector section
of the annular chamber, i.e., the inner and outer
radial portions of the annular chamber respectively;
Figure 4 illustrates a radial view of the
invention generally viewed along broken line A-A' in
Figure 3, and shows the rotor, fan, diffuser channel
and collector section of the annular chamber;
Figure 5 illustrates a view of the diffuser
channel and the collector section taken along the
broken line of B-B' in Figure 4;
JOY 03030
Figure 6 illustrates a slightly diverging
diffuser channel along a portion of the broken line
By in Figure 4;
Figure 7 shows the vane diffuser channel from
a radian view similar to the view in Figure 4 but
extending through the entire diffuser channel;
Figure 8 illustrates a vane diffuser channel
generally viewed along a portion of the line C-C' in
Figure 7;
Figure 9 illustrates a cooling system schematic
for a reverse flow, gas cooled dynamo electric machine
which utilizes a purely radial flow fan, and includes
a diffuser channel and a collector section as part of
the annular chamber.
Detailed Description of the Drawings
Figure 1 illustrates a partially cutaway
perspective view of the cooling system for a reverse
flow, gas cooled dynamo electric machine 10. Only one
end of the dynamo electric machine 10 is illustrated
in Figure 1. The outboard extension 14 of a rotor .
extends outward from machine 10. Inside a frame
wrapper 16, not visible from Figure 1's perspective,
is a stators Figure 1 further illustrates an inner
end wall shield 17 which is axially spaced apart from
an outer end wall shield 19. An annular chamber 40
is defined between shield 17 and shield 19. A fan 30
is located radially coextensive with annular chamber
40 at one end of the rotor. The fan's exhaust port
34 is clearly illustrated in Figure 1.
A disk 23 is located in the radially inner
portion of annular chamber 40. Disk 23 is mounted to
shield 19 proximate one axial side of fan exhaust
port 34. Disk 23 has an inboard surface 25 which it
substantially parallel to the adjacent surface
portion of shield 17. A diffuser channel 42 is
defined by the radially inner surface portion
of shield 17 and inboard surface 25 and the channel
16
JOY 03030
--8--
receives substantially all of the gas flow expelled
by fan 30~ Disk 23 has an outboard surface 27 which
is opposite inboard surface 25 and which is spaced
away from shield 19. Radially beyond disk 23 it an
S outer collector section 44 of annular chamber
A clearer understanding or the annul chamber
yea n ~,~
and its associated members can ye eye from the
cooling system schematic shown as Figure 2. The
numerals labeling various elements of the
dynamo electric machine in Figure 1 are carried
forward throughout all the Figures. An inboard
portion 12 of the rotor is illustrated in Figure 2.
A stators 18 and rotor 12 are surrounded by frame
wrapper 16. Means for cooling 26, which could be
dome cooler well known in the art, is located atop
frame wrapper 16. Cooling means 26 does not
circumferential surround frame wrapper 16 but is
disposed along an arcuate portion of frame wrapper
16~ The intake ductwork 29 of the cooling means is
clearly illustrated as cutaway in Figure 1 and is
shown in Figure 2. In this particular machine, fan
30 is a mixed flow fan which circulates gas
throughout the cooling system as shown by the heavy
narrowed lines in Figure 2.
Generally, the gas is drawn from the region of
stators 18 and rotor 12 and is expelled radially
outward from exhaust port 34. The gas is expelled
both radially and circumferential into annular
chamber 40r therefore, fan 30 is termed a mixed flow
fan herein but the fan exhibits primarily radial flow
characteristic with some axial flow characteristics
as clearly illustrated in the figures. Intake
ductwork 50 of cooling means 26 is associated with
ductwork 29 and an arcuate port 51 in frame wrapper
16. Port 51 provides communication of the gas
between annular chamber 40 and the cooling means.
The gas is cooled therein and the output of cooling
means 26 is split into an outboard flow path 52 and
17 GE 0 3 0 3 0
go
an inboard flow path 54. Flow path 52 is associated
with an outer annuls ductwork which funnels the gas
from path 52 radially inward towards through passage
56 to a slotted spindle 32 on the rotor. Thereafter,
the gas flows through the relative stall passages
in the rotor copper. Inboard flow path 54 passes
through passages in frame wrapper 16 and other
smaller passages in stators 18. The gas flow through
both rotor 12 and stators 18 is then combined in the
a r gap of the dynamo electric machine. Of course,
not all the gas flows through stators 18 but some gas
enters the interior spaces of frame wrapper 16 as
illustrated by the arrows in Figure 2.
Specifically, the gas is drawn into fan 30
axially near spindle 32. the static pressure head of
the gas is increased by fan 30 and the velocity
pressure head is alto produced by f an 1 5 rotation .
Elence, the gas expelled through fan exhaust port 34
has an initial static pressure head and an initial
velocity pressure head. Substantially all of the gas
expelled is received by diffuser channel 42.
Diffuser channel 42 transforms a portion of the
velocity pressure head into static pressure head
thereby increasing the total static pressure head of
the gas above the initial static pressure head. The
gas leaving diffuser channel 42 enters the outer
radial portion of the annular chamber or the
collector section 44.
Collector section 44 collects the gas exiting
diffuser channel 42 with minimal loss of the static
pressure head of the gas and minimal disturbance of
any residual velocity head, thereby minimizing any
heating of the gas as a result of edgy streams
created within the annular passage. Collector
section 44 communicates with cooling means 26 only
through arcuate port 51 in the frame wrapper 16.
Elence, although collector section 44
circumferential surrounds diffuser channel 42, the
loge 03030
- 1 0 -
gas only exits collector section 44 through port 5 1 .
In other words, annular chamber 40 is limited
radially by frame wrapper 16, therefore gas flow is
directed into cooling means 26 with minimal disturbance by passions through the collector section.
As stated earlier, outboard surface 27 of disk
23 is spaced away from shield lo ~11 overhang
collector section 45 is therefore defined by surface
27 and shield 19. The collector disclosed and
claimed herein includes both overhang collector
section 45 and collector section 44. Overhang
section 45 allows the gas to flow in the annular
chamber without the introduction of substantial eddy
streams therein. it its believed overhang section 45
lo increases the efficiency of the cooling system
by allowing the gas to flow in the annular chamber
without significant disturbances. To insure minimum
eddy team losses and heat gain, the thickness of
disk is minimized. Hence, overhang section 45 is
maximized but not at the expense of diffuser channel
42 which must be substantially parallel to shield 17
and have a significant radial extent to transform a
portion of the gas' velocity head into static
pressure head.
Although fan diffusers are fairly well known,
the space limitations inherent in dvnamoelectric
machines described herein severely limit the type,
shape, and effectiveness of diffuser which can be
incorporated into the machines. Specifically, the
ratio of the radial distance between the rotor
centerline and exhaust port 34, labeled R1 in
Figure 2, and the radial distance between frame
wrapper 16 and the centerline of the rotor, R2, is
large, on the order of I Fan diffusers usually
have radii ratios on the order of 1/4 and lower.
Therefore, incorporating a fan diffuser into
Lyle JOY 03030
dynamo electric machines is severally limited by the
ratio of the radii, herein 1/2. It would not be
economical to radially or axle expand frame
wrapper 16~ the axial space available for the
diffuser charnel and associated collector section is
limited because of the bearing span of the outboard
portion of the rotor. The configuration of diffuser
channel 42, collector section 44 and overhang section
45 in annular chamber 40, as described herein, is
relatively easy to incorporate, both structurally and
monetarily, in dynamo electric machines within the
radial and axial space available without extensive
modifications of the machine.
It has been calculated for a reverse flow, once
through, four pole dynamo electric machine, operating
at 1800 RPM with a mixed flow fan and a diffuser
channel occupying 22% of the total volume of the
annular chamber, a collector section occupying 52% of
the total volume and an overhang section occupying
approximately 26% of the total volume, the static
pressure of the gas exiting the annular chamber will
be increased on the order of 16% over a machine
without the fan diffuser and collector combination
described herein. This estimated increase in static
pressure should increase the flow of gas through the
machine and hence improve the cooling system of the
machine.
Figure 3 is a blow up of the most significant
portions of Figures 1 and 2 which include mixed flow
fan 30 and annular chamber 40~ Chamber 40 includes
diffuser channel 42, collector section 44 and
overhang section 45 as well as the items proximate
the annular chamber. In a similar fashion to Figure
2, the general direction of the flow of gas is
indicated by arrows in Figure 3.
Fan 30 includes intake port 60 which is
proximate slotted spindle 32. Inner end plate shield
17 extends radially from one axial side of exhaust
loge 03030
port 34 to frame wrapper 16. A sealing means is
provided between the radially inner portion 62 of
inner shield 17 and the side owe exhaust port 34. The
outer end plate shield 19 extend radially froth the
ether axial end of exhaust port 31 to points radially
coextensive with the frame wrapper 16 and also
includes a sealing means. Diffuser section 42 is
defined by inboard surface Z5, and portion 62 of
shield 17 wherein inboard surface 25 is substantially
parallel Jo the adjacent surface of portion 62. Disk
23 is mounted by means 68 to shield 19.
Disk 23 is supported axially away from shield 17
by one of a plurality of airfoil supports 70. The
supports are located in diffuser channel 42 at
substantially evenly spaced intervals circumferen-
tidally about the rotor. Support 70 is a small
airfoil which allows gas to flow around it without
disturbing the flow and thereby minimizing any eddy
streams which may occur in the gas flow as a result
of the presence of the supports. the airfoil
supports are oriented parallel to the stream lines of
the gas flow to minimize the eddy streams in the gas
flow.
Disk 23 has a radially outer end portion 72
which is preferably a bulb shape. Bulb shaped end 72
allows the gas which exits diffuser channel 42 to
flow smoothly around disk 23 and into collector
section 44 and overhang section 45 without
significantly disturbing the streamlines of the flow.
Disk 23 is foreshortened with respect to frame
wrapper 16. In the illustrated machine, the disk it
approximately one half the radial extent of the frame
wrapper. A round support 74 axially spaces shield 17
from shield 19. Other items numbered in Figure 3
have been discussed earlier with respect to Figures 1
and 2.
Figure 4 is an axial view looking towards the
rotor taken along broken line A-A' in Figure 3. Line
I JOY 03030
-13-
A A' runs through collector section 44 and overhang
section 45, through disk 23 and then radially through
a portion of diffuser channel 42, fan 30, slotted
spindle 32 and the rotor 14. The numerals
designating these and other items in ire 4 art
similarly designated figures 1, 2 and 3.
Specifically, viewing Figure 4 from the centerline of
the rotor radially outward, rotor 12 is illustrated,
slotted spindle 32, fan 30 and the edge of exhaust
port 34 is noted. Disk 23 is then shown. Airfoil
support 70 and the other supports in the channel
appear as dashed lines because the radial end view is
taken from a plane axially cut through overhang
section 45 which is the space between disk 23 and
shield 19. The orientation of airfoil supports 70
are detailed in Figure 4 as being parallel to the
flow of gas exiting discharge. port 34 of fan 30~ End
72 of disk 23 is shown in Figure 4. Round support 74
noted as is within collector section 44. The outer
edge of frame wrapper 16 is also illustrated in
Figure 4. As clearly illustrated in Figure 4, frame
wrapper 16, as represented by its outer edge 65,
radially encloses a substantial portion of collector
section 44, and hence annular chamber 40. Since the
gas flows substantially radially outward from fan 30
and cooling means 26 only communicates with the
chamber through arcuate port 51, collector section 4
and overhang section 45 provide a volume of space
within which the gas flows without substantially
increasing eddy streams and creating back flow
pressure in the gas
Although the gas flows primarily radially
through chamber 40, the gas does possess a
circumferential velocity component. To prevent the
gas which enters overhang section 45 from circulating
completely around the annular chamber, a blocking
means or back block 80 is disposed in the overmans
section 45 at a position which would guide the gas
I JOY 03030
flowing clockwise in Figure 4 upwards towards cooler
means 26. Similarly, a cutoff foil 82 or directing
means completely blocks off the circular flow of gas
in collector section 44. Cutoff foil 82 and back
5 block 80 are downstream of the arcuate port and
hence Roth direct the gas upwards towards the intake
OX cooler means 26. Cutoff foil 32 is located at a
circumferential position such that the flow of gas is
directed radially upward towards the cooler means.
The diffuser channel and collector section is
illustrated in Figure 5 as seen from the view of
dashed line B-B' in Figure 4. Figure 5 is a partial
view of the diffuser channel 42 and collector section
44 taken through back block 80 and cutoff foil 82.
It is to be understood that the velocity head of
the gas is transformed into static pressure head by a
substantially parallel walled annular diffuser
channel which is disposed in the annular chamber
immediately downstream of the fan's exit. However,
the diffuser channel could be slightly diverging as
illustrated in Figure 6. Figure 6 shows a three
degree divergence from the throat of channel 42 to
the exit of that channel. For purposes of this
invention, a divergence on the order of 3 degrees is
considered substantially parallel.
The diffuser channel 42 could include a
plurality of vanes 90 oriented such that the vanes'
centerline are substantially parallel to the
stream lines of the gas flowing through channel 42 as
illustrated in Figure 7. Figure 8 illustrates the
location of a vane in diffuser channel 42. Figure 7
illustrates a complete end view of the vane diffuser
channel and shows the orientation of the vanes'
centerlines with respect to vane 90. The end view of
Figure 7 runs through collector section 44, diffuser
channel I as well as fan 30, slotted spindle 32 and
rotor 12. For clarity only vane 90 is illustrated in
- 15 - JOY 3030
its entirety. However, the centerlines of the
remaining vanes are illustrated in Figure 7. The
plurality of vanes may assist in transforming the
velocity head of the gas flowing through diffuser
channel 42 into static pressure head at the exit of
that channel.
Figure 9 is a schematic for a cooling system
which includes a radial flow fan 101 as part of a reverse
flow, dynamo electric machine. Fan 101 is affixed to
spindle 32 of the rotor and draws gas from the interior
of frame wrapper 16 into annular chamber 40. As in
earlier illustrations, similar numbers denote similar
components of this dynamo electric machine. The operation
of the diffuser channel, collector section and overhang
section is substantially the same with radial flow fan
101 as is the operation of mixed flow fan described
hereinabove.
It is to be understood that a fan diffuser could
be utilized at both ends of the dynamo electric machine
to increase the efficiency of a dual cooling system.
It is also to be noted that the overhang section 45 could
be axially opposite that as described herein. In other-
words, shield 19 could define diffuser channel 42 in come
bi.nation with disk 23. In that particular case, disk 23
would be mounted to shield 17 and overhang section I
would be defined between disk 23 and shield 17.
person ordinarily skilled in the art could
practice the invention with the principles described
herein by utilizing a diffuser channel as part of the
annular chamber in combination with a collector. The
specific configuration of the disk, diffuser channel
supports, cooler location, or the general configuration
of the annular chamber is only illustrative of a fan
diffuser and associated collector and overhang sections
described and claimed herein. For example, a person of
ordinary skill in the art could practice the present
it
- 16 - JOY 3030
invention by having a parallel walled diffuser channel
defined by a disk, an overhang section defined by
the outboard surface 27 of the disk and by having
supports extending between shield 19 and outboard
surface 27 rather than the support shown in the diffuser
channel. The disk could be an integral par-t of shield
19 or shield 17 rather -than a separate structure as
illustrated herein. Also, square supports and a
squared off disk end would transform the velocity head
into static pressure head/ however -the efficiency of
the fan diffuser and associated collector would not be
as great as calculated hereinabove.
It is estimated that the static pressure head
recovered -from the gas flow could be improved on the
order of 15 -to 35 percent with a fan diffuser assembly
as described herein.
The pending claims are intended to cover all
of the above modifications and other apparatus which fall
within the true spirit and scope of the present
invention.
