Improvements in Governors for Elastio Fluid Turbines.
Year: 1896

page_text: Date of Application, ist Sept., 1898-Accepted, 21st Nov., 1896
COMPLETE SPECIFICATION.
Improvements in Governors for Elastio Fluid Turbines.
I, CLAUDE KENNEDY MILLS, of 23 Southampton Buildings, in the County of
London, Patent Agent, do hereby declare the nature of this invention, a com-
munication to ine from Charles Gordon Curtis, Engineer, of 441 Park Avenue,
New York City, in the County of New York and State of New York, in the
United States of America, and in what mauner the same is to bo performed, to
be particularly described and ascertained in and by the following statement :-
The invention relates to apparatus for developing power from steam or other
elastic fluid under pressure, wherein the energy of pressure is converted into energy
of velocity or vis viva, and is transformed into mechanical power by being directed
against a portion of the vanes of a complete circular range of rotating vanes, or by
being directed successively against a portion of two or more sets of such vanes.
In all elastic fluid turbines, mechanical power is developed by utilizing the vis viva
of the fluid to impart motion to the blades or vanes of the turbine. The principles
uuderlying the successful solution of the problem of developing mechanical power
by means of such turbines in an efficient practical and commercially satisfactory
manner have been embodied by the communicator in apparatus upon which Letters
Patent have been applied for simultaneously herewith. In all successful mechanical
combinations by which this result can be obtained with steam or other clastic fluid,
the size, form and relative proportions of all the parts which unite to form the
passage way through which the fluid passes from the source of supply under
maximum pressure to the exhaust, are necessarily adapted to permit expansion of
the fluid and conversion of its pressure into velocity, and to convert the maximum
amount of vis viva into rotary motion of the vanes, during its passage from inlet to
exhaust.
Having planned and constructed such an apparatus in a manner to produce the
greatest possible mechanical power when the maximum volume of fluid is admitted
thereto, the problem of governing such a machine efficiently prescuts itself, that
is to say, of insuring the same relatively high efficiency under all variations
of load,
This has not heretofore been accomplished. The invention has for its object the
solution of this problem.
For the majority of commercial purposes requiring a stationary plant, an elastic
fluid turbine, like a steam engine, inust be made to maintain a practically constant
speed under all variations of load. The new apparatus for governing is based upon
the principle that if the volume of the jet of the clastic Huid flowing through a
turbine is made to vary, and at the same time the velocity of the jet remain
constant, the mechanical power developed will vary as the volume of the jet varies,
and therefore the efficiency of the turbine will be substantially the same at all loads.
Furthermore, if the volume of the jet is made to vary substantially as the load
varies, but the velocity of the jet is constant, the speed of rutation of the turbine
will remain constant.
On the other hand, it has been found that if both the velocity and volume of
the jet at the point or points where it strikes the vanes of the turbine are varied
the speed of rotation of the turbine will vary, or if the speed of rotation is under
these conditions maintained constant a relatively larger volume of jet will be
required to maintain this speed of rotation at light than at heavy loads; and in
either case there will be a loss in efficiency.

page_text: In carrying out the invention a governing mechanism is provided which is 80
designed as to vary the volume of the jet to any desired extent without varying its
velocity at the point or points where it acts upon the movable element or elements
of the turbine, that is to say, where this velocity is converted into mechanical
power. This is done by maintaining the same relative proportions between the
parts of the expansion passage way while varying the size of the steam inlet i.e. the
volume of the jet at its entrance to the apparatus from the source of supply.
With the oldest and best known form of expansion nozzle, i.e. one having
diverging sides and gradually enlarging cross sections, variation of the size of the
sn aller end only i.e. of the volume of the jet admitted to the nozzle, will bo
attended with variation of the velocity of the jet at the larger end, for the volocity
of the jet at the larger end will depend upon the amount of expansion that has
occured at that point, and if the nozzle is designed to permit full oxpansion at the
larger end when the smaller end is wide open, full expansion will occur before the
jet reaches that point, if the smaller end is partly closed, and the consequence will
be that the cross section of the larger end will be too large to convey the reduced
volume of fluid at the proper velocity and a reduced velocity at this point will
follow. As the eis riva or energy contained in the moving fluid varies as the
square of its velocity, a comparatively slight loss of velocity results in a very
considerable loss of power. In order therefore that the degree of expansion and
therefore the velocity of the jet may be constant at the larger or delivery ond under
variations in the size of the smaller end, it is essential that the cross section of the
larger end shall at all times bear the same proportion to the cross section of the
smaller end, and the rate of cross sectional increase between the two remain
constant.
Whether this or some other form of expansion nozzle is used, or whether the
expansion is allowed to take place partly in the stationary passages and partly in
the movable or secondary elements of the apparatus, the essential thing is that
variation in the fluid inlet, i.e. in the volume of fluid admitted from the source of
supply, shall be accompanied by such variation in the controlling parts of the
expansion passage way through which the fluid jet passes to the exhaust (i.e. those
parts where the fluid acts upon the movable elements of the turbine and where for
that rensen it is important to maintain the proper velocity or velocities) as shall
maintain at all times the same proportions between the various parts and the fluid
inlet. Under these conditions the volume of the jet will vary, but its effective or
virtual velocity at each point where it acts will remain substantially constant under
variations in volume.
The apparatus constructed by the communicator embodying these principles of
governing show the marked improvement in efficiency, economy and commercially
satisfactory practice which is a condition precedent to an extensive use of steam or
elastic fluid turbines as prime inovers.
lu carrying out the invention in conuection with a turbine having only one set
ol vanes or buckets to which motion is imparted by the vis riva of the fluid jet, the
conversion of the pressure of the fluid into velocity should preferably precede its
impact with that portion of each vane which is designed to convert such velocity
into mechanical power. The means for obtaining such conversion may be either
the old diverging nozzle or an improved expansion nozzle devised by the com-
inunicator in which the fluid issues from a contracted inlet or nozzle into a larger
passage whose cross section may be constant and equal to the volume of the jet
when the desired expansion has taken place. Describing this part of the apparatus
as the expansion passage or nozzle, it is inade adjustable so that the cross section
of the fluid inlet may be varied and so that every variation thereof shall be
accompanied by simultaneous variations in the other parts of the expansion passage,
and the proportions between them remain constant. The adjustable element inay
be moved by hand but of course an automatic adjustment by means of a speed
governor or otherwise is necessary for most purposes. The adjustability may be
obtained in different ways. In the case of the diverging form of nozzle, one side

page_text: thereof may be adjustable towards and away from the other side, or both sides may
be adjustable towards and away from each other; or the single nozzle may be
divided into a number of separate expanding passages more or fewer of which may
be closed by a movable gate.
In case one side of the nozzle is made adjustable, this adjustable side may be
piece having a movement in a right line, in which case the proportion between the
inlet and the discharging ends will be roughly maintained not only within narrow
limits of inlet variation, unless the nozzle be made with its movable side parallel to
the one opposite, and the other two sides diverging, (but so that the cross section
of the nozzle shall be a parallelogram), the increase of cross section being thus
obtained, and the proportions maintained regardless of the adjusted distance
between the parallel sides or the proportion may be maintained with precision by
pivoting the adjustable element of the nozzle, or moving it in curved guides, so that
it will have a greater rate of motion at the discharging end than at the inlet end of
the nozzle, the rate of motion being proportional to the respective cross sectional
areas at these points.
In applying the invention to the case of an expansion passage of other than the
diverging form the expansion passage is made practically of two parts (one being a
contracted inlet or nozzle, and the other a larger discharge end) and these parts
aro constructed so that by means of movable walls or parts, the cross sectional
arens of both the inlet and discharge may be caused to vary simultaneously and
proportionally.
In applying the invention to a turbine having two or more sets of rotating vanes
in which the ris rica is utilized, and an inlet nozzle or passage and one or more
stationary or rotating intermediate expanding passages, the principle underlying
correct governing is the same. The whole passage way through which the fluid is
passing at any instant from the supply to the exhaust may be considered as made
up of sections or portions in which (1) pressure is converted into vis viva, (2) the
direction of flow of the jet is changed as required, and (3) the vis viva is converted
so far as possible into mechanical power. Any section may perform only one of
these functions or it may combine two or more of them. With reference to
governing in accordance with the invention it is necessary that all controlling cross
sections of the passage way considered as a whole should vary simultaneously with
every change at the inlet end, and maintain at all times the same proportions to
each other. With respect to any portion of the passage way which is made up of
spaces between vanes or buckets, the adjustable element of the passage way which
immediately precedes will determine the number of vanes to which the jet is
admitted at any instant by the cross section of its discharge end at that instant.
Every portion of the passage way not made up of spaces between vanes will have
an adjustable side whose movement, whether on a pivot, or sliding etc., will effect
the proportionate variation required and simultaneity of variation will be obtained
by connecting all the adjustable sides to appropriate mechanism whereby all will
move with every movement given to the adjustable side at the inlet, whether by an
automatic speed controlling device, or otherwise.
Another class of turbines may be considered in which the passage way through
which the steam or fluid passes may be regarded as divided into a series of passage
ways each in some sense complete in itself, the first beginning at the inlet from the
main steam supply and ending at an exhaust pipe leading from the first shell to
the beginning of the second passage way, this exhaust pipe serving as a supply pipe
to the second passage way and so on, the apparatus being divided up into parts,
each operating under a lower initial pressure than the one before it. In this case
invention does not require any variation in the various exbaust pipes thus described,
but only that each of the series of passage ways shall be varied throughout simul-
taneously and proportionally with each variation of its own inlet, and that all the
inlets after the first shall vary simultaneously and proportionally with the one
opening from the main steam supply. The application of the invention to this case
is similar to that described above, except that what has been called the exhaust

page_text: pipes, (regarding them now as portions or seations of the entire steam passage) are
not varied but remain constant, tho velocity of the steam or fluid being at auch
points trifling and unaffected by them in any way.
In the accompanying drawings, forming part hereof:
Fig. 1 is a side elevation of a simple or non-compounded turbine, having the
invention applied thereto;
Fig. 2 is a sectional view of the same apparatus through the nozzle and exhaust
passage, with the vanes developed in a horizontal plane, and showing the well
known diverging nozzle with the invention applied thereto;
Fig. 3 is a diagram indicating a new construction of expansion nozzle or expansion
intermediate stationary passage;
Fig. is a section similar to Fig. 2, showing a different construction of the
adjustable element of the nozzle, and illustrating the invention applied to a
compound turbine having a divided or sectional adjustable intermediate stationary
passage;
Fig. 5 is a view similar to Fig. 4, and of the same character of apparatus, showing
a different method of adjusting the nozzle;
Fig. 6 is a sectional view similar to Fig. 5, illustrating the employment of
a divided or sectional nozzle, and a single or undivided adjustable intermediate
stationary passage;
Fig. 7 is a sectional view of an expansion nozzle or stationary passage, showing
a different method of adjustment ;
Fig. 8 is a side elevation, illustrating the construction of Fig. 7 applied to the
nozzle and intermediate passages of a compound turbine having a series of
connected moveable elements located in separate shells; and
Fig. 9 is a radial section of the apparatus of Fig. 8, taken on a line running
through the centre of the steam passages.
Referring to Figures 1 and 2, A is a steam tight shell, within which is mounted
upon a shaft B, a disc C, carrying on its periphery a complete circular range of
curved vanes a. Entering one side of the shell A is tho delivery nozzle D, and
from the other side of the shell leads the exhaust opening E, which may open into
the air or be connected with a condenser or other means for producing less than
atmospheric pressure. Leading to the nozzle D is the pipe F from the steam boiler
or other source of elastic fluid under pressure. The nozzle D is of the well known
type having diverging sides and gradually enlarging cross sections between its
throat or receiving end b, aud its discharging end c.
The purpose of this nozzle is to convert the energy of pressure into energy of
velocity or vis viva.
The relation between the discharging end cand the receiving end 6 is determined
by the conditions of velocity which it is desired to obtain at the delivery end of the
nozzle. It is highly important that the velocity at which the steam is designed to
be delivered to or to act upon the vanes should be maintained practically the same,
whatever volume of steam is passing, because it is by means of the velocity that
the machine does its work, and to do this it is necessary that the proportions
between the two ends of the nozzle, whatever they are in the particular design of
the machine, should be maintained substantially constant, and it is this which the
invention is designed to accomplish. In order to diminish the volume or quantity of
steam flowing, and at the same time obtain approximately the same efficiency in the
operation of the apparatus, one of the diverging sides of the nozzle D is formed by
a plate G, which slides in suitable ways d within the auxiliary shell e, an opening,
being made from the steam pipe F into the space within the shell e to more nearly
balance the pressure on the plate G. The sliding movement of the plato G is
Becured by means of a rod f passing through a stuffing box g. This rod may be
connected by a link with a bell crank lever H, which lever is connected at its
other end with the sliding collar i of a centrifugal governor located within the
wheel I, so that the adjustment of the plate G will be produced automatically by a
small percentage of variation in the speed of the turbine. It will be understood

page_text: that by making one of the diverging sides of the nozzle adjustable from end to end
of the nozzle, the relations between the points b and c will be roughly maintained
within narrow limits of inlet variation and the velocity of the steam as it is
discharged from the nozzle will be approximately the same for all volumes of
the steam jet within a limited range of adjustment of the nozzle. If however the
adjustable side be made parallel with the opposite side of the nozzle and the
expansion is obtained by the divergence of the other two aides (the form in
cross section being a parallelogram) any degree of adjustment can be obtained
without changing the desired relations.
The nozzle, instead of having regularly diverging walls and gradually increasing
cross sections as illustrated in Fig. 2, may be made in a different form, such as, for
example, the construction illustrated diagrammatically in Figure 3, in which there
is a contracted inlet or nozzle b of proper size and a larger discharging end c of
proper size to give the desired expansion, the walls between these points being
parallel; and it should be understood that such construction is considered to be an
expansion," nozzle or an "expansion" intermediate passage within the meaning of
that word as applied to auch nozzles and passages in this specification.
Instead of adjusting the nozzle by means of a plate moving in a right line, as in
Figures 1 and 2, the end of this sliding plato may be a pivoted piece K, having a
curved tailpiece k, held to its curved seat by a spring I, and balanced by a steam
opening e so that as the piece K is pushed forward, it will be turned on its
pivot sufficiently to preserve with precision the relations between the receiving and
discharging ends of the nozzle, by giving it a greater rate of movement towards
the other side of the nozzle at the discharging end o thau at the receiving
end 6, these different rates of movement being proportional to the different cross-
sectional areas at those points. Or, as illustrated in Fig. 5, the adjustable
piece K may be pivoted at a point sufficiently removed from the nozzle to
preserve the proper relation by a pivotal movement of the piece.
somewhat different construction shown in Fig. 7 is considored an excellent
form. In this, the movable piece K slides on a curved seat, and is moved
forward and backward by means of a rack m, with which engages a pinion n on
a spindle o extending through the side of the nozzle, or it may be moved by
a sliding rod as in other constructions shown. In Fig. 6 a construction of
adjustable nozzle is shown wherein the nozzle is divided into a number of diverging
sections by partitions p, more or less of the sections of the nozzle being closed, by a
sliding gate L.
The
In applying the invention to a compounded turbine, the stationary intermediate
passage (or each of them if the compound turbine has more than two movable
elements) is divided into a number of sections by curved vanes q, as shown in
Figures 4 and 5. This construction secures an adjustment of the stationary
passage simultaneously and proportionally with the adjustment of the nozzle,
because the number of the sections of the stationary passage occupied by the
steam jet in passing from one set of movable vanes to another will depend upon the
number of movable vanes from which the jet is discharged, and that number is in
turn dependent upon the adjustment of the nozzle. It is preferred however to
provide a single or non sectional intermediate passage M, and have one of its
sides N adjustable towards and away from the other side throughout the length of the
passage, as shown in Fig. 6, or only at the discharging end of the passage, as
shown in Fig. 8. In Fig. 6, the adjustable side N of the stationary passage M is
a separate piece, closing one side of the passage and moving between the parallel
side walls towards and away from the other side of the passage, the movement
being secured by a sliding rod which is preferably adjusted simultaneously with
the adjustment of the nozzle. The construction illustrated in Figures 8 and 9 is a
compound turbine composed of three movable elements O, O', O' contained in
separate shells and connected to receive the flowing jet in succession by means of in-
termediate stationary passages P, P', which are provided with adjustable discharging
nozzles of the character illustrated by Fig 7, Q is the inlet pipe from the steam

page_text: boiler, and Q is the exhaust opening, discharging into the air, or connected with a
condenser. The steam passes from the inlet Q to the vanes of the first turbine through
a nozzle having an adjustable element like that illustrated in Fig. 7. The nozzle
and the discharging ends of the intermediate passages are adapted to successively
convert different portions of the pressure into velocity. The spindles to whose
inner ends carry the pinions for adjusting the movable pieces K, as illustrated in
Fig. 7, have on their outer ends, pinions engaging with rack bars R, which in
turn engage with pinions a, connected together in any suitable way, as by a single
rack bar S, whereby the adjustable elements of the expansion nozzle and the
expansion intermediate stationary passages may all be moved simultaneously and to
the same extent.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. A governor for elastic fluid turbines, acting to cause variations in the volume
of the fluid jet unaccompanied by substantial variations in its velocity at the point
or points where it acts upon the moving parts to develop mechanical power,
substantially as set forth.
2. In an elastic fluid turbine, the combination with a set of rotating vanes, of an
expansion nozzle or stationary passage acting to convert pressure into velocity,
such nozzlo or passage being adjustablo to vary the volume of the fluid whilo
maintaining approximately the ratio or degree of expansion of the fluid in the
nozzle or passage, substantially as set forth."
3. In a compound elastic fluid turbine, the combination of movable vanes to
which the fluid is delivered two or more times in succession by a nozzle and one or
more intermediate stationary passages, such nozzle and intermediate passage or
passages being simultaneously and proportionately variable in their cross sectional
areas, whereby the volume of the elastic fluid may be varied unaccompanied by
substantial variations in its velocity at the two or more points where it acts on the
movable vanes, substantially as set forth.
4. In a compound elastic fluid turbine, the combination with two or more sets of
rotating vanes, of an adjustable expansion nozzle, one or more intermediate
stationary passages having adjustable expansion discharging ends, and a connection
between the adjusting devices of the nozzle and intermediate passages whereby the
adjustment of the nozzle and of the ono or more intermediate passages will be
effected simultaneously and proportionately, substantially as set forth.
Dated Sertember 1st 1896.
HARRIS & MILLS,
23 Southampton Buildings, London, W.C., Agents.
HARRIS & MILLS,
23 Southampton Buildings, London, W.C., Agents.