Improvements in Centrifugal Fans and Pumps.
Year: 1898

page_text: Date of Application, 14th Sept., 1898
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Improvements in Centrifugal Fans and Pumps.
I, SAMUEL CLELAND DAVIDSON, of Sirocco Engineering Works, Belfast, Ireland,
Merchant, do hereby declare the nature of this invention to be as follows:-
My improvements relate to centrifugal fans or pumps in which the fluid
operated on is taken in centrally and discharged circumferentially, and more
particularly to those wherein I employ blades which are of considerably greater
axial length than radial depth, and said depth as shallow as is practicable, con-
sistent with strength of construction; in combination with an intake opening
or eye thereto of a diameter of not less than ths of that of the circumference
of the outer edges or tips of the blades, and with the portions of the intermediate
spaces or ports between the blades which are within the circumference of said
intake opening or eye, open at the ends towards the inflowing fluid; and my
improvements also relate to the type of fan represented in Figure 7 of the
drawings forming part of my Specification No. 24510 of 1894.
The object, amongst others, of my present invention is to so control and guide
the fluid after it is discharged circumferentially from the outer edges or tips
of the blades of said fans or pumps (hereinafter referred to as the fans) and which
discharge takes place in tangentially directed streams from the ports or spaces
between the blades and with more or less of an eddy space between each of said
streams owing to the obstruction due to the thickness or form of each individual
blade, that these streams shall be gradually focussed or compressed together
within a collecting and discharging chamber around the exterior circumference
of the blades either attached to the fan and revolving therewith or applied
around same as a fixture or a part of its enclosing casing, wherein the fluid is
gradually guided from either or both ends of the blades into a continuous open-
ing or channel around the outer circumference of said collecting chamber and
so far compressed thereby that at time of its discharge therefrom it is free from
said eddy spaces, whereby an improved efficiency is obtained in said fans, whether
same be operating within a spiral casing, or with a free or unencased discharge
all round the circumference.
My invention consists in constructing fans or pumps of the type and construc-
tion hereinbefore described with a collecting, guiding and discharging chamber
around same. This chamber may either be attached to the fan and revolve
therewith, or be applied around same as a fixture, or form part of the enclosing
casing thereof, but is preferably formed by rims or annuli (hereinafter referred
to as the rims) one at each end of the blades, extending beyond their outer
circumference, and so applied thereon that they revolve therewith and that the
outer edges of said rims converge towards one another, but terminate at such a
distance apart that the open space between them forms a continuous and open
channel or exit around said collecting chamber. I preferably make the circum-
ferential area of this channel equal to or less than the area of the intake opening
or eye of the fan. When said fans are constructed with said collecting chamber

page_text: and are used for drawing the fluid they are operating on, from a building and
to deliver same with free discharge into the open air, the said collecting, guiding
and discharging chamber not only improves the strength and velocity of dis-
charge from the fan in calm weather, but if a strong wind be blowing against
the side of the building on which the discharge is being made, the rims protect
the blades therefrom, and tend to deflect the wind into same direction as that
of the discharge, without retarding said discharge to any appreciable extent;
this is an important advantage on large exposed buildings such as factories;
while when used within a spiral casing enclosing said fan it improves the pres-
sure of the discharge when the latter is operating against a back pressure.
Dated this 14th day of September 1898.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London,
Chartered Patent Agents.
ашрготещение и сениниgal rans апи гитры.
I, SAMUEL CLELAND DAVIDSON, of Sirocco Engineering Works, Belfast, Ireland,
Merchant, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
My improvements relate to centrifugal fans or pumps (hereinafter referred to
as the fans) in which the fluid operated on is taken in axially and discharged
circumferentially, and particularly to those wherein the fluid has a free discharge
from the fan all around its periphery and wherein blades are employed which
are of considerably greater axial length than radial depth, and the ports between
which are freely open towards the entering fluid, no side plates being employed
therewith for closing the ends of the blades.
In fans of the aforesaid type the fluid after it is discharged circumferentially
from the outer edges or tips of the blades in approximately tangentially directed
streams from the ports or spaces between the blades, has more or less of an eddy
space intervening between each of said streams owing to the obstruction due to
the thickness or form of each individual blades which separates the streams
axially, and the object amongst others of my present invention is to so control
and guide the fluid after it has been discharged from the outer edges or tips of
the blades as above described, that said outwardly flowing streams shall be
gradually condensed or concentrated within an outwardly narrowing and con-
tinuous opening or channel (hereinafter referred to as the concentrating channel)
around the outer circumference of said blades, whereby the fluid after issuing
from the ports between the blades is so far concentrated in passing through said
concentrating channel that at time of its discharge therefrom it is free from said
eddy spaces whereby an improved efficiency is obtained in said fans when in
other respects said fans operate with a free or unencased discharge all round their
circumference, while the strength and velocity of discharge from the fan are
increased by the employment of the concentrating channel, owing to the open
area of its outer circumference being less than that of its inner circumference.
According to my present invention fans or pumps of the type and construction
herein before described are constructed with a concentrating channel or collecting
chamber around same which may either be attached to the fan and revolve
therewith, or one side of same may be applied as a separately mounted fixture

page_text: around the aperture through which the fluid is admitted into the fan. Said
concentrating channel, as regards one side thereof is formed by an extension of
the disc on which the blades are mounted, beyond the outer circumference of
said blades, and the opposite side of a rim or annulus formed approximately as
the cross section of a hollow cone, the narrow end of which is in one modification
of my invention, attached to the outer circumference of the opposite ends of the
blades from that which is attached to the disc, and revolves therewith, and in
another modification attached as a fixture around the opening or aperture through
which the fluid enters the fan and in both modifications said annulus is not of
less diameter at its narrowest part than the outer circumference of said blades
so that an intake opening or eye to the fan can be employed therewith of approxi-
mately equal diameter to that of the outer circumference of the blades.
The outer edge of the disc and of said annulus consequently converge towards
one another, but are kept at such a distance apart that the open space between
them forms a continuous and open channel or exit around said concentrating
channel and I preferably make the circumferential area of this channel equal
to or less than the area of the intake opening or eye of the fan. When said
fans are constructed with said concentrating channel and are used for drawing
the fluid they are operating on from a building and to deliver same with free
discharge into the open air, said concentrating channel not only improves the
strength and velocity of discharge from the fan in calm weather, but if a strong
wind be blowing against the side of the building on which the discharge is
being made, the outwardly extended part of the disc tends to deflect the wind
from the blades into same direction as that of the air being discharged from the
fan without retarding said discharge to any appreciable extent which is an im-
portant advantage on large exposed buildings such as factories.
In the accompanying drawings:-
Figure 1 is a longitudinal section of a centrifugal fan or pump in which my
present invention is embodied the concentrating channel being constituted by
rims or annuli at the ends of the blades and revolving therewith.
Figure 2 is a longitudinal section illustrating a modification in which one
side or rim of the concentrating channel is applied around the fan or pump as
a fixture, so as not to revolve with the fan, while the other side or rim is a
continuation of the disc of the fan and revolves therewith.
The arrows in the figures indicate the course of the fluid which passes through
the fan or pump.
Referring first to Figure 1, a a represent the blades; they are fixed at one
end to a disc b, and at the other end which is the intake end to a ring c which
connects all the blades together at this end. d is the revolving shaft on which
the disc carrying the blades is mounted. In both the modifications represented
the eye or intake of the fan is shown of the same diameter as that of the cir-
cumference of the outer edges or tips of the blades; and although
prefer that
the diameter of said eye should be equal to that of said circumference of the
tips of the blades it may be somewhat smaller. e is the concentrating channel
formed by the two rims f. g. The rim f is an extension of the disc b and is
bent slightly inwards, the rim g is attached to the ring c and slopes towards the
rim f so that the two rims f and g converge towards each other at their outer
edges.
In the modification shown in Figure 2 the rim f (as in Figure 1) is an exten-
sion of the disc of the fan so as to revolve therewith while the rim g forming
the other side of the concentrating channel is applied around the fan or pump
as a fixture. Or the rim f may be applied as a fixture as well as the rim g.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:
1. In centrifugal fans and pumps wherein the fluid operated upon is admitted

page_text: axially and discharged circumferentially with a free or unencased discharge
therefrom all around the periphery of the fan or pump, a concentrating channel
around the periphery of the fan or pump, one side of said channel being an out-
ward extension of the disc on which the blades are mounted, and beyond the
outer circumference of said blades, and the other side being an annulus in the
form of the cross-section of a hollow cone concentric, with the fan or pump,
the narrow end of said cone being around the orifice through which the fluid
enters the fan or pump without extending within the outer circumference of
the blades over the ends of the ports between said blades, substantially as herein-
before described.
2. In centrifugal fans and pumps wherein the fluid operated upon is admitted
centrally and discharged circumferentially with a free or unencased discharge
therefrom all around the periphery of the fan or pump, a concentrating channel
around the periphery of the fan or pump, one side of said channel being an out-
ward extension of the disc on which the blades are mounted, and beyond the
outer circumference of said blades, and the other side being an annulus in the
form of the cross-section of a hollow cone concentric with the fan or pump, the
narrow end of said cone being attached to the outer periphery of the fan or
pump around the opposite ends of the blades from those which are attached to
said disc, and so as to revolve therewith, and without extending inwards towards
the centre of the fan or pump over the ends of the ports between said blades,
substantially as set forth.
3. In centrifugal fans and pumps wherein the fluid operated upon is admitted
centrally and discharged circumferentially with a free or unencased discharge
therefrom all around the periphery of the fan or pump, the combination of
blades which are of considerably greater axial length than radial depth, a disc
upon which said blades are mounted at one end, said disc extending the whole
way from the fan or pump shaft outwards and preventing the passage of fluid
at this end of the fan or pump, an intake opening or eye to said fan or pump of
a diameter approximately equal to that of the circumference of the outer edges
of said blades, the intermediate spaces or ports between said blades being open
at their ends towards the inflowing fluid, and a concentrating channel around
the periphery of the fan or pump one side of said channel being an outward
extension of said disc beyond the outer circumference of said blades and the other
side being an annulus in the form of the cross-section of a hollow cone concen-
tric around said intake opening or eye without extending within the outer cir-
cumference of the blades over the ends of said ports, substantially as herein-
before described.
Dated this 8th day of June 1800
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London,
Chartered Patent Agents.