Improvements in Screw Fans and Pumps for Propelling Air, Gases, or Liquids.
Year: 1896

page_text: Date of Application, 10th Aug., 1896
Complete Specification Left. 10th May, 1897-Accepted, 12th June, 1897
PROVISIONAL SPECIFICATION.
Improvements in Screw Fans and Pumps for Propelling Air, Gases,
or Liquids.
I, The Honourable CHARLES ALGERNON PARSONS, of Heaton Works, New-
castle-on-Tyne, in the County of Northumberland, Engineer, do hereby declare
the nature of this invention to be as follows:-
When screw fans or propellors are used for propelling air, gases, or liquids it is
usual to place the propellor within a ring or within the conduit or pipe through
which the gas or liquid is required to be forced. I find however that the efficiency
of the screw pump is affected to a very great extent by the form of the ring or
conduit in the neighbourhood of the propellor, and that while a screw pump working
in a ring or in a conduit of uniform area is comparatively inefficient, yet by making
the tube around the propellor of proper form and proportions, a very high degree
of efficiency may be reached.
I find that the flow of gas or liquid from the blades of the propellor is far from
uniform, and that it is necessary to prolong the ring around the propellor to a
distance of from 2 to 3 or more diameters in length in order to mingle the currents.
I find that this increases the efficiency by more than 50 per cent.
I further find that by making the tube in the form of a gently diverging cone,
the efficiency is further increased and lastly I find that the entry to the ring
for the best results must be a converging cone or a converging trumpet mouth.
By these means I am enabled to gently accelerate the gas or liquid in the entry
to the screw propellor up to a suitable velocity for the propellor to work in to the
best advantage with a moderate slip ratio and high intrinsic efficiency. On leaving
the propellor the irregular velocity of the several parts of the column, mingle and
become nearly homogeneous in velocity, in the parallel or gently diverging cone,
and their energy is thereby utilized or conserved while still moving at high velocity.
On passing throngh the diverging cone the kinetic energy is converted into potential
energy of pressure.
In practice I find that a gently diverging cone of 3 to 4 diametere, nearly doubles
the efficiency of the same propellor working in a tube of one diameter only in length.
Instead of using a gently diverging cone throughout behind the propellor, I may
use a parallel tube of one or two diameters or more and add to it a gently diverging
cone.
I may also instead of placing the propellor within the entry to the diverging
cone, place it at a short distance in front or behind of the smallest section of the
casing.
I may use this propellor in conjunction with my well known steam turbine or
I may drive it by an electro-motor or from any other suitable source of power, and
I am hereby enabled to move much larger volumes of gas or liquid than is
possible with a centrifugal fan or pump of similar dimensions and first cost, and
1 am also hereby able to construct a fan or pump with a higher rotational speed
than is possible with a centrifugal fan or pump, and in many cases I am hereby
able to use my steam turbine for driving the fan or pumps, which would not be
otherwise economically possible. In many cases such a fan or pump
for the same

page_text: reason, is more suitable for working in conjunction with electro motors or any high
speed motors.
Dated this 10th day of A nonet 1806
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.
Improvements in Screw Fans and Pumps for Propelling Air, Gases,
or Liquids.
I, The Honourable CHARLES ALGERNON PARSONS of Heaton Works, New-
castle-on-Tyne, in the County of Northumberland, Engineer 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 invention relates to that class of fan or pump in which the air, gas or liquid
is propelled in the desired direction by the action of helices or partial helices fixed
upon a rotating boss.
My invention consists in forming the casing in which the propeller works of certain
relative dimensions and configuration and in constructing the feed pipe or channel
to the pump or fan in the shape of a converging cone or trumpet mouth while the
exit is arranged in the form of a diverging cone.
When sorew fans or propellers are used for propelling air, gases or liquids, it is
usual to place the propeller within a ring or within the conduit or pipe through
which the air, gas or liquid is required to be forced. I find however, that the
efficiency of the screw pump is affected to a very great extent by the form of
the ring or conduit in the neighbourhood of the propeller, and that while a screw
pump working in a ring or in a conduit of uniform area is comparatively ineffi-
cient, yet by making the tube around the propeller of proper form and proportions
a very high degree of efficiency may be reached.
I find that the flow of air, gas or liquid from the blades of the propeller is
far from uniform and that it is necessary to prolong the ring around the
propeller to a distance of from one to three or more diameters in length in
order to mingle the currents. I find that this increases the efficiency by more
than 30 per cent.
I further find that by making the tube in the form of a gently diverging cone
the efficiency is further increased, and lastly I find that the entry to the ring for
the best results must be a converging cone or a converging trumpet mouth.
By these means I am enabled to gently accelerate the air gas or liquid in the
entry to the screw propeller up to a suitable velocity for the propeller to work in
to the best advantage with a moderate slip ratio and high intrinsic efficiency. On
leaving the propeller the irregular velocity of the several parts of the column,
mingle and become nearly homogeneous in velocity in the parallel or gently
diverging cone and their energy is thereby utilized or conserved while still moving
at high velocity. On passing through the diverging cone the kinetic energy is
converted into potential energy of pressure.
In practice I find that a gently diverging cone of 3 to 4 diameters, nearly doubles
the efficiency of the same propeller working in a tube of one diameter only in
length. Instead of using a gently diverging cone throughout behind the propeller,
I may use a parallel tube of one or two diameters or more and add to it a gently
diverging cone.

page_text: 1 may also instead of placing the propeller within the entry to the diverging
cone, place it at a short distance in front or behind of the smallest section of the
casing.
I may use this propeller in conjunction with my well known steam turbine, or
I may drive it by an electro motor or from any other suitable source of power, and
I am hereby enabled to move much larger volumes of air, gas or liquid than is
possible with a centrifugal fan or pump of similar dimensions and first cost. I am
also hereby enabled to construct a fan or pump with a higher rotational speed than
is possible with a centrifugal fan or pump, and in many cases to use my steam
turbine for driving the fan or pumps, which would not be otherwise economically
possible. In many cases such a fan or pump for the same reason, is more
suitable for working in conjunction with electro motors or any high speed motor.
The accompanying drawings illustrate two modes of carrying my invention into
effect as applied to the propulsion of air and gases.
Figure 1 is a sectional elevation in which my improved propeller driven by
one of my steam turbines is applied to produce suction draught in a colliery.
Figure 2 is a plan partly in section of my improved propeller as applied for
inducing draught in the flue of a boiler or furnace.
Referring to Figure 1 of the drawings I arrange a screw propeller A within
a ring casing B which is constructed about one diameter in length, and on the top
of the drift or uptake C I fix a trumpet shaped or converging pipe D the smaller
diameter being attached to the ring casing while the larger is fixed to the drift
or uptake. Upon the other side of the ring casing I fix the bottom and smaller
end of the funnel E, the said funnel gradually diverging and increasing in
diameter to its termination. To actuate the propeller AI preferably arrange
one of my well known steam turbines such as that shown at F connected to the
propeller by the shaft G though any other high speed motor may be used.
The forced draught caused by the foregoing arrangement is of very high efficiency
for the reasons hereinbefore fully described.
Referring now to Figure 2 of the drawings wherein an application of my inveu-
tion to the forcing of air or gases is illustrated. I arrange a screw propeller H upon
a shaft 1, actuated by one of my steam turbines revolving within a ring casing K
and having the air or gas supply passage L gently converging and therefore
decreasing in diameter from K¹ to K' where it meets the ring casing, while the
exit M gently diverges from K to K and therefore increases in diameter from
the ring casing to the point of delivery K shown on the drawing.
application of my invention high efficiency in forcing air or gases is secured and for
the reasons herein before fully described.
By this
It is to be clearly understood that this arrangement of converging supply passages
and diverging delivery passages leading to and from a parallel or other casing
containing a screw propeller driven at high velocity by a steam turbine or other
rapidly rotating motor is the main feature of my invention while it is obvious that
it is capable of application for use in producing forced or induced draught on board
ship and in fact that it may be universally applied.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. In means for the propulsion of air, gases or liquids the provision of a gently
converging casing or passage up to the propeller working therein and a gently
diverging casing or passage from the propeller substantially for the purpose
described.
2. In means for the propulsion of air, gases or liquids where a gently converging
supply passage or casing and a gently diverging delivery passage or casing are used,
the provision of a parallel ring casing containing the propeller to which the supply
and delivery casings are connected, substantially as described.

page_text: 3. Improvements in means for the propulsion of air, gases, or liquids substantially
as bereinbefore described; and also substantially as illustrated in the accompanying
drawings.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.