IMPROVEMENTS IN ROTARY OR CENTRIFUGAL MACHINES POR ACTING UPON AIR, WATER, AND OTHER FLUIDS. AND COMMUNICATING MOTIVE POWER, THEREBY
Year: 1868

page_text: LETTERS PATENT to Thomas.. Webster Rammell, of 3, Westminster
Chambers; Westminster, in the County of Middlesex, Civil
Engineer, for the Invention of "IMPROVEMENTS IN ROTARY OR
CENTRIFUGAL MACHINES POR ACTING UPON AIR, WATER, AND OTHER FLUIDS.
AND COMMUNICATING MOTIVE POWER, THEREBY,"
.
PROVISIONAL SPECIFICATION left by the said Thomas Webster
. Rammell at the Office of the Commissioners of Patents, with his
Petition, on the 21st August 1868.
I, THOMAS WEBSTER RAMMELL, of 3, Westminster Chambers,
Westminster, in the County of Middlesex, Civil Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN ROTARY
OR CENTRIFUGAL MACHINES FOR ACTING UPON AIR, WATER, AND OTHER FLUIDS,
AND COMMUNICATING MOTIVE POWER THEREBY," to be as follows:-
In the construction of rotary or centrifugal machines for the working
of pneumatic railways, the ventilation of mines, and other like
purposes, in which large quantities of air have to be dealt with, it has
[Prios 8d.]

page_text: hitherto been the practise to make the internal ducts or passages
and the discharge vents in collective transverse area as large as or
larger than the central apertures on either side through which the
air is admitted. In the ordinary ventilating fan the ducts or passages
increase in size from the central parts of the machine outwards, and at
the discharge vents are many times larger in collective area than the
apertures for admission. In my centrifugal discs the internal passages
or compartments of the disc are directed to be of such shape that
each compartment shall be of the same or nearly the same transverse
area throughout at whatever distance from the centre a section be
taken, and that the sum of all the compartments may be equal or
nearly equal to that of the aperture at the centre through which the
air is admitted. These proportions however are found to be productive
of inefficiency and loss of power in the use of the machine, and one of
my improvements consists in reducing the size of the ducts and
discharge vents relatively to that of the central apertures. I make
this reduction in such manner that while at their commencement
around the line of junction with the central apertures the ducts are
collectively equal in transverse area to those apertures they become
gradually smaller and smaller as they extend outwards, and are
smallest where they terminate in the discharge vents at the rim or
periphery of the machine. I also regulate the degree of the reduction
to be given in each case by making it correspond to the intensity
of the work to be performed by the machine. Thus if the intended
velocity of the entering air at the central apertures and the mouths
of the ducts is equal to 1 and its intended velocity at the discharge
vents equal to 2 I reduce the transverse area of the vents to half
or nearly half that of the ducts at their mouths.
If the respective
velocities are to be as 1 to 3 I reduce the area of the vents to one-
third, or nearly, of that of the ducts at their mouths, and so on,
always making the area at each part correspond to the intended
velocity of the fluid there and adequate to pass the volume.
In arriving at these improved proportions I am guided by the
following considerations:-It is in all cases desirable that the central
apertures should be of full size in order that the air may enter the
machine freely, and at the lowest practicable velocity, and as a rule
they should be equal or nearly equal in area to the transverse
section of the main air-way or supply shaft with which they are in
communication.
But whatever be the velocity at which the air

page_text: ..
enters, a much higher rate has to be given to it in its passage through
the machine in order to the obtaining of the working pressure
required, and which it is the object of the machine to produce, and
this higher rate must, from the nature of the machine, be gradually
communicated to the fluid by rotary or centrifugal action, and be at
its maximum intensity at the point of discharge. Since, then, the
air leaves the machine at a higher velocity than it enters it, and
the increased rate is gradually impressed upon it, it is clear that the
discharge vents may be of less collective area than the central
apertures, and also that in certain proportions the ducts inay be
gradually reduced down to the size of the vents without affecting the
capacity of the machine. The true form, indeed, for the ducts of rotary
or centrifugal machines would appear to be one gradually dimishing
in size from their commencement at the central apertures to their
termination in the vents, the degree of diminution at each part being
in inverse proportion to the increase of velocity there communicated
to the fluid by the rotation of the machine, due allowance being made
in the degree of diminution for the increased surface friction consequent
upon the contraction of the ducts.
Machines thus proportioned will be found both more efficient and
more economical in, use than any hitherto constructed, they pro-
vide for the admission of the air with the least possible expenditure
of power upon the draught; they insure a steady and regular increase
in the flow of the current through the ducts, and a firm jet from the
vents; they present a minimum surface of rib and also of section of
current to the external resistance at the vents; and they save the
waste occasioned by unnecessarily whirling round in the machine at
high velocity and in a most disturbed state, owing to its contact with
the external atmosphere, a surplus quantity of air before it is discharged.
Another of my improvements consists in the placing of the machine
in the underground workings of a mine in such manner that the
ventilation may be effected partly by drawing the current towards the
machine by exhaustion, and partly by sending the current from the
machine under compression after it has been passed through it.
In other respects I adhere to the forms and modes of construction
described in my previous Patents for improvements in similar machines,
and I claim the improvements herein set forth as applicable not only
to rotary or centrifugal machines intended for use with air and other
}

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Webster Rammell, in the Great Seal
Patent Office on the 19th February 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
WEBSTER RAMMELL, of No. 3, Westminster Chambers, Westminster,
in the County of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of August, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-first year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said Thomas Webster
Rammell, Her special licence that I, the said Thomas Webster
Rammell, my executors, administrators, and assigns, or such others
as I, the said Thomas Webster Rammell, my executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN ROTARY OR
CENTRIFUGAL MACHINES FOR ACTING UPON AIR, WATER, AND OTHER FLUIDS,
AND COMMUNICATING MOTIVE POWER THEREBY," upon the condition (amongst
others) that I, the said Thomas Webster Rammell, my executors
or administrators, by an instrument in writing under my, or their, or
one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Thomas Webster Rammell, do
hereby declare the nature of my said Invention, and in what
manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
In the construction of rotary or centrifugal machines for the working

page_text: of pneumatic railways, the veutilation of mines, and other like purposes
in which large quantities of air have to be dealt with, it has hitherto
been the practise to make the internal ducts or passages, and the
discharge vents in collective transverse area as large as or larger than
the central apertures on either side through which the air is admitted.
These proportions however are found to be productive of inefficiency
and loss of power in the use of the machine.
And one of my Inventions consists in gradually reducing the size of
[ make
the radiating ducts or passages from their mouths outwards.
this reduction in such manner that while at their junction with the
central apertures, that is to say, at their mouths, the ducts are collectively
equal in transverse area to the sum of the areas of the two apertures,
they become gradually smaller and smaller in proportion as they extend
outwards, and are smallest where they terminate in the discharge vents
at the rim or periphery of the machine. I regulate in each case the
degree of reduction given according to the intensity of the work to be
performed.
Thus if the intended velocity of the entering current at
the central apertures, and at the mouths of the ducts, be equal
to 1, and its intended velocity at the discharge vents be equal to 2,
I reduce the transverse area of the ducts at the vents to one-half
If the intended velocities at
or nearly one-half of that at their mouths.
mouth and vent be respectively as 1 to 3, I reduce the area of the
vents to one-third or nearly one-third of that of the mouths, and so on.
In reducing the ducts I make the transverse area at each part pro-
portionate, though in an inverse ratio, to the intended increase of
velocity to be there communicated to the current, and thus adequate
only to pass the volume of the current, taking care however to provide
for the maximum quantity intended to be thrown.
In arriving at these improved proportions I am guided by the following
considerations:-It is in all cases desirable that the central apertures
should be of full size in order that the current may enter the machine
freely and at a velocity not exceeding that it has already acquired in
As a rule therefore
the main communicating air way or supply shaft.
I prefer to make the united area of the central apertures equal or
nearly equal to the transverse sectional area of such main air way or
supply shaft. But whatever be the velocity at which the air enters the
machine, a much higher rate has to be given to the current in its
passage through the radiating ducts in order to obtain the working

page_text: pressure required, and which it is the object of the machine to produce,
and this higher rate from the nature of the machine being gradually
communicated by rotary or centrifugal action will attain its maximum
flow only at the rim or periphery, where the current is discharged.
Since, then, the fluid leaves the machine at a higher velocity than it
enters, and no more can be discharged than enters, it is clear that the
discharge vents may be of less collective area than the central apertures
and the mouths of the ducts; and also that as the increase of velocity
is gradually communicated, the radiating ducts may be gradually
reduced in size from the mouth out to the vent without affecting the
capacity of the machine. The true form indeed for the radiating ducts
of rotary or centrifugal machines would appear to be one gradually
diminishing in size from the mouth to the vent, the degree of diminu-
tion made at each part being in inverse proportion to the increase of
velocity there communicated to the fluid by the rotation of the machine,
due care being always taken to keep the ducts of sufficient size to pass
the maximum quantity ever intended to be thrown. The proportions
of the ducts will thus vary in each case according to the intensity of
the work to be performed.
In the accompanying Drawing Fig. 1 is a front view, and Fig. 2
a side view of the main portion of a rotary or centrifugal machine,
the central apertures of which are indicated at C, C, the rim or
periphery at D, D', and one of the radiating ducts at A, A', and B, B¹.
In this case the intended velocity of the current where it enters the
central apertures is supposed to be equal to 1, and its intended velocity
when discharged from the vents equal to 2, the rate of flow being
doubled. The discharge vents are therefore made of only one-half the
transverse area of the mouths of the ducts, and the transverse areas of
each duct at the equidistant points shown by the lines a, a, b, b, c, c¹³,
d, d, and e, e', are respectively equal to 1, to ths, to ths, to ths,
and to ths; that is to say, they are in inverse proportion to the
increase in the angular velocity of rotation at each.
Fig. 1 is a front view, and Fig. 3 a side view, with the same letters
of reference, of a similar machine with which the intended velocities of the
current at entry and discharge are supposed to be equal to 1 and 4
respectively. In this case the vents of the radiating ducts are made
one-fourth only of the area of the mouths, and the transverse areas
on the equidistant lines a, b, b, c, c, d, d', and e, e¹, are respectively

page_text: equal to 1 to 13ths, to 18ths, to ths, and to ths, being in inverse
proportion to the increase in the angular velocity of rotation at each.
In designing machines I proceed upon this method in all cases in
determining the proportions of the ducts, varying the diameter of the
machine and that of the central apertures, and the length, and the size
at mouth of the radiating ducts, and the degree of diminution given
according to the circumstances of each. In other respects I adhere
to the forms and modes of construction described in my former Patents
for improvements in similar machines.
Another of my Inventions consists in the placing of the machine in
the underground workings of a mine in such manner that the ventila-
lation may be effected partly by drawing the current towards the
machine by exhaustion, and partly by sending the current from the
machine under compression after it has been passed through it.
Figures 4, 5, and 6 represent respectively a plau, a longitudinal
section, and a transverse section of this arrangement.
A, A, B, B', is a main air course of a mine communicating between
the up-cast and the down-cast shafts, and upon which in an enlarge-
ment the machine itself is placed. The two former letters indicate
the backward portion of the course coming from the down-cast shaft,
the two latter the forward portion leading towards the up-cast, the
direction of the current being shown by the arrows; C, C¹, and D, D¹,
are side passages or chambers for admitting the current to the central
apertures, and also for receiving the engines for driving the machine;
F, F, and G, G, are air-tight partitions separating the backward from the
forward portion of the course. The manner of placing the machine
itself and the engine or engines for driving it will be readily understood
from the Drawings without further description. In operation it may be
stated the air is rarified by the rotation of the machine to the degree
requisite to produce the draught desired from the down-cast shaft and
bring the current through the back ward workings, and through A, A¹,
C, C¹, and D, D¹, to the central apertures and into the machine, and by
the same movement also it is thrown from the vents into the chamber
or passage B, B', in that state of compression necessary for driving the
current onwards through the forward workings and out through the
up-cast shaft, and so effecting the ventilation of the nine. If the
machine be placed near the bottom of the down-cast shaft the ven-
tilation will be chiefly performed by compression, if near the bottom

page_text: of the up-cast shaft it will be chiefly done by exhaustion, and if mid-
way between the two shafts it will be performed half by exhaustion
and half by compression. When the workings are sufficiently extensive
to require it, I use two or more machines at a convenient distance (say
a mile or so) apart, placing them in such manner that the one in
advance takes up the current from the other behind and again sends it
onwards. By this arrangement I am enabled to carry on the ventilation
of a mine to an indefinite extent, since there is no limit to the number
of the machines that may be thus employed. I am also enabled to keep
down the pressure required for the ventilation within any desirable limit
by limiting the distance between the machines. I also employ the
machine with advantage in aid of existing means of ventilation, by
using it for the movement of the current through special portions of the
workings where from their great length or other cause difficulty is now
experienced in keeping up the flow, and in this manner and in com-
bination with existing means or otherwise am enabled to extend the
workings beyond their present limits.
Figures 7 and 8 show an arrangement of two machines placed upon
the same air course, the one in advance of the other and at any con-
venient distance apart. When duplicates are desired I either place the
machines in enlargement side by side, or as represented in the last
Figures one in advance of the other. The advantage of the latter
arrangement is that the two machines may be worked together at a lower
velocity of rotation than either singly to produce the pressure required,
the one in advance taking up and continuing the working of the other
behind. For the greater compactness of the machine and convenience
of transporting it and fixing it in the underground workings I some-
times place the bearings of the shaft in the pieces connecting the
central apertures with the exhaust passages on either side.
I prefer
to make these connecting pieces of cast-iron, and each in two halves,
an upper and a lower, so that they may be readily put together on
the spot and bolted down to the foundations prepared. This arrange-
ment is shown at e, e¹, e, e¹, Figures 4, 5, and 6, and by it all the
main metal work of the machine apart from the prime mover is limited
to that contained in the rotating disc itself with its its shaft, and in these
two connecting pieces constituting also the bearings and footings. I
make the joint between the fixed and the moving parts by the con-
trivance shown at f, f1, Figure 3, which will be readily understood.

page_text: From this description it is obvious that other forms of rotary machines
might be arranged in a similar manner and for the like object in
underground workings, and although they could not be so conveniently
introduced and in action they would be much less efficient, some
advantage over the present system might be derived from their use.
Such rotary machines might be upon what is called the centrifugal
principle or upon the principle of the fan, or that of the screw, or
that of the pump, and they might be placed so as to rotate in a plane
either parallel to the direction of the air course or at some angle to
it, and either horizontally or vertically. It is unnecessary that I should
give any further description or drawings of the manner of fixing such
machines, as the various methods of adapting them to the general
arrangements I have set out will readily occur to any practical person.
I do not confine myself to the particular arrangements above
described, but what I claim as the Invention secured by the said Letters
Patent is,
-
1. The form and construction of rotary or centrifugal machine
described and any form of such machine in which the radiating ducts
gradually diminish in size in whatever degree as they extend outwards
from the centre.
2. The arrangement and placing of the machine in the underground
workings of a mine as described for its ventilation in the manner
described, and any similar arrangement and placing of the same or
any similar machine or of any rotary machine in underground workings
for the like object.
In witness whereof, I, the said Thomas Webster Rammell, have
hereunto set my hand and seal, this Sixteenth day of February,
One thousand eight hundred and sixty-nine.
T. W. RAMMELL. (L.S.)