Nikola Tesla: Disk Turbine / Pump (Articles, patents, links)


![](0logo.gif)  
 **[rexresearch.com](../index.htm)**

---

**Nikola TESLA**

**Disc Turbine/Pump**  

---

**[*New York Herald Tribune* (15 Oct.
1911) *~* "Tesla's New Monarch of Machines"](#nyt)**
  
**[*Scientific American* (30 September
1911), p. 290 ~ "From the Complex to the Simple"](#sciam1)**   
**[*Scientific American* (30 September
1911), p. 296 ~ "The Rotory Heat Motor Reduced to its
Simplest Terms"](#sciam2)**   
**[E. Stearns: *Popular Mechanics
Magazine* (December 1911) ~ "The Tesla Turbine"](#popmech)**
  
**[Nikola Tesla: US Patent # 1,061,142 ~
"Fluid Propulsion"](#1061142)**   
**[N. Tesla: US Patent # 1,061,206 ~
"Turbine"](#1061206)**   
**[N. Tesla: US Patent # 1,329,559 ~
"Valvular Conduit"](#valvcond)**   
**[Links](#links)**

**[Page 2](turbine2.htm) >>**

**N. Tesla: British Patent # 179,043 ~ "Production of High
Vacua" // N. Tesla: British Patent # 186,082 ~ "Improvements
in the Construction of Steam and Gas Turbines" // N. Tesla:
British Patent # 186,083 ~ "Economic Transformation of the
Energy of Steam by Turbines" // N. Tesla: British Patent #
186,084 ~ "Improved Process & Apparatus for Deriving
Motive Power from Steam" // N. Tesla: British Patent #
186,799 ~ "Process & Apparatus for Balancing Rotating
Machine Parts"**

**[Page 3](turbine3.htm) >> R. Hedin: "The
Tesla Turbine" (Construction Plans); *Live Steam*
(Nov. 1984) // Warren Rice: "Tesla Turbomachinery"; Proc. IV
International Nikola Tesla Symposium (Sept. 23-25, 1991)**

---

**Nikola Tesla**   
![](portrait.jpg)

---

***New York Herald Tribune* (15 Oct. 1911) *~***


**"Tesla's New Monarch of Machines"**

Suppose some
one should discover a new mechanical principle -- something as
fundamental as James Watts discovery of the expansive power
of steam -- by the use of which it became possible to build a
motor that would give ten horse power for every pound of the
engine's weight, a motor so simple that the veriest novice in
mechanics could construct it and so elemental that it could
not possibly get out of repair. Then suppose that this motor
could be run forward or backward at will, that it could be
used as either an engine or a pump, that it cost almost
nothing to build as compared with any other known form of
engine, that it utilized a larger percentage of the available
power than any existing machine, and, finally, that it would
operate with gas, steam, compressed air or water, any one of
them, as its driving power.

It does not
take a mechanical expert to imagine the limitless
possibilities of such an engine. It takes very little effort
to conjure up a picture of a new world of industry and
transportation made possible by the invention of such a
device. "Revolutionary" seems a mild term to apply to it.
That, however, is the word the inventor uses in describing it
-- Nikola Tesla, the scientist whose electrical discoveries
underlie all modern electrical power development, whose
experiments and deductions made the wireless telegraph
possible, and who now, in the mechanical field, has achieved a
triumph even more far reaching than anything he accomplished
in electricity.

There is
something of the romantic in this discovery of the famous
explorer of the hidden realms of knowledge. The pursuit of an
ideal is always romantic, and it was in the pursuit of an
ideal which he has been seeking twenty years that Dr. Tesla
made his great discovery. That ideal is the power to fly -- to
fly with certainty and absolute safety -- not merely to go up
in an aeroplane and take chances on weather conditions, "holes
in the air", tornadoes, lightning and the thousand other
perils the aviator of today faces, but to fly with the speed
and certainty of a cannon ball, with power to overcome any of
nature's aerial forces, to start when one pleases, go whither
one pleases and alight where one pleases. That has been the
aim of Dr. Tesla's life for nearly a quarter of a century. He
believes that with the discovery of the principle of his new
motor he has solved this problem and that incidentally he has
laid the foundations for the most startling new achievements
in other mechanical lines.

There was a
time when men of science were skeptical -- a time when they
ridiculed the announcement of revolutionary discoveries. Those
were the days when Nikola Tesla, the young scientist from the
Balkans, was laughed at when he urged his theories on the
engineering world. Times have changed since then, and the
"practical" engineer is not so incredulous about "scientific"
discoveries. The change came about when young Tesla showed the
way by which the power of Niagara Falls could be utilized. The
right to divert a portion of the waters of Niagara had been
granted; then arose the question of how best to utilize the
tremendous power thus made available -- how to transmit it to
the points where it could be commercially utilized. An
international commission sat in London and listened to
theories and practical plans for months.

Up to that
time the only means of utilizing electric power was the direct
current motor, and direct current dynamos big enough to be of
practical utility for such a gigantic power development were
not feasible.

Then came
the announcement of young Tesla's discovery of the principle
of the alternating current motor. Practical tests showed that
it could be built -- that it would work.

That
discovery, at that opportune time, decided the commission.
Electricity was determined upon as the means for the
transmission of Niagara's power to industry and commerce.
Today a million horse power is developed on the brink of the
great cataract, turning the wheels of Buffalo, Rochester,
Syracuse and the intervening cities and villages operating
close at hand the great new electro-chemical industries that
the existence of this immense source of power has made
possible, while all around the world a thousand waterfalls are
working in the service of mankind, sending the power of their
"white coal" into remote and almost inaccessible corners of
the globe, all because of Nikola Tesla's first great epoch
making discovery.

Today the
engineering world listens respectfully when Dr. Tesla speaks.
The first announcement of the discovery of his new mechanical
principle was made in a technical periodical in mid-September,
1911. Immediately it became the principal topic of discussions
wherever engineers met.

"It is the
greatest invention in a century", wrote one of the foremost
American engineers, a man whose name stands close to the top
of the list of those who have achieved scientific fame and
greatness.

"No
invention of such importance in the automobile trade has yet
been made", declared the editor of one of the leading
engineering publications. Experts in other engineering lines
pointed out other applications of the new principle and
letters asking for further information poured in on Dr. Tesla
from the four quarters of the globe.

"Oh, I've
had too much publicity", he said, when I telephoned to him to
ask for an interview in order to explain his new discovery to
the non-technical public. It took a good deal of persuasion
before he reluctantly fixed an hour when he would see me, and
a good bit more after that before he talked at all freely.
When he did speak, however, he opened up vistas of possible
applications of the new engine that staggered the imagination
of the interviewer.

Looking out
over the city from the windows of his office, on the twentieth
floor of the Metropolitan Tower, his face lit up as he told of
his life dream and its approaching realization, and the
listener's fancy could almost see the air full of strange
flying craft, while huge steamships propelled at unheard of
speeds ploughed the waters of the North River, automobiles
climbed the very face of the Palisades, locomotives of
incredible power whisked wheeled palaces many miles a minute
and all the discomforts of summer heat vanished as marvelous
refrigerating plants reduced the temperature of the whole city
to a comfortable maximum -- for these were only a few of the
suggestions of the limitless possibilities of the latest Tesla
discovery.

"Just what
is your new invention?", I asked.

"I have
accomplished what mechanical engineers have been dreaming
about ever since the invention of steam power", replied Dr.
Tesla. "That is the perfect rotary engine. It happens that I
have also produced an engine which will give at least
twenty-five times as much power to a pound of weight as the
lightest weight engine of any kind that has yet been produced.

"In doing
this I have made use of two properties which have always been
known to be possessed by all fluids, but which have not
heretofore been utilized. These properties are adhesion and
viscosity.

"Put a drop
of water on a metal plate. The drop will roll off, but a
certain amount of the water will remain on the plate until it
evaporates or is removed by some absorptive means. The metal
does not absorb any of the water, but the water adheres to it.

"The drop of
water may change its shape, but until its particles are
separated by some external power it remains intact. This
tendency of all fluids to resist molecular separation is
viscosity. It is especially noticeable in the heavier oils.

"It is these
properties of adhesion and viscosity that cause the 'skin
friction' that impedes a ship in its progress through the
water or an aeroplane in going through the air. All fluids
have these qualities -- and you must keep in mind that air is
a fluid, all gases are fluids, steam is fluid. Every known
means of transmitting or developing mechanical power is
through a fluid medium.

"Now,
suppose we make this metal plate that I have spoken of
circular in shape and mount it at its centre on a shaft so
that it can be revolved. Apply power to rotate the shaft and
what happens? Why, whatever fluid the disk happens to be
revolving in is agitated and dragged along in the direction of
rotation, because the fluid tends to adhere to the disk and
the viscosity causes the motion given to the adhering
particles of the fluid to be transmitted to the whole mass.
Here, I can show you better than tell you."

Dr. Tesla
led the way into an adjoining room. On a desk was a small
electric motor and mounted on the shaft were half a dozen flat
disks, separated by perhaps a sixteenth of an inch from one
another, each disk being less than that in thickness. He
turned a switch and the motor began to buzz. A wave of cool
air was immediately felt.

"There we
have a disk, or rather a series of disks, revolving in a fluid
-- the air", said the inventor. "You need no proof to tell you
that the air is being agitated and propelled violently. If you
will hold your hand over the centre of these disks -- you see
the centres have been cut away -- you will feel the suction as
air is drawn in to be expelled from the peripheries of the
disks.

"Now,
suppose these revolving disks were enclosed in an air tight
case, so constructed that the air could enter only at one
point and be expelled only at another -- what would we have?

"You'd have
an air pump", I suggested.

"Exactly --
an air pump or blower", said Dr. Tesla.

"There is
one now in operation delivering ten thousand cubic feet of air
a minute. Now, come over here."

He stepped
across the hall and into another room, where three or four
draughtsmen were at work and various mechanical and electrical
contrivances were scattered about. At one side of the room was
what appeared to be a zinc or aluminum tank, divided into two
sections, one above the other, while a pipe that ran along the
wall above the upper division of the tank was connected with a
little aluminum case about the size and shape of a small alarm
clock. A tiny electric motor was attached to a shaft that
protruded from one side of the aluminum case. The lower
division of the tank was filled with water.

"Inside of
this aluminum case are several disks mounted on a shaft and
immersed in a fluid, water", said Dr. Tesla. "From this lower
tank the water has free access to the case enclosing the
disks. This pipe leads from the periphery of the case. I turn
the current on, the motor turns the disks and as I open this
valve in the pipe the water flows."

He turned
the valve and the water certainly did flow. Instantly a stream
that would have filled a barrel in a very few minutes began to
run out of the pipe into the upper part of the tank and thence
into the lower tank.

"This is
only a toy", said Dr. Tesla. "There are only half a dozen
disks -- 'runners', I call them -- each less than three inches
in diameter, inside of that case. They are just like the disks
you saw on the first motor -- no vanes, blades or attachments
of any kind. Just perfectly smooth, flat disks revolving in
their own planes and pumping water because of the viscosity
and adhesion of the fluid. One such pump now in operation,
with eight disks, eighteen inches in diameter, pumps four
thousand gallons a minute to a height of 360 feet."

We went back
into the big, well lighted office. I was beginning to grasp
the new Tesla principle.

"Suppose now
we reversed the operation", continued the inventor. "You have
seen the disks acting as a pump. Suppose we had water, or air
under pressure, or steam under pressure, or gas under
pressure, and let it run into the case in which the disks are
contained -- what would happen?"

"The disks
would revolve and any machinery attached to the shaft would be
operated -- you would convert the pump into an engine", I
suggested.

"That is
exactly what would happen -- what does happen", replied Dr.
Tesla. "It is an engine that does all that engineers have ever
dreamed of an engine doing, and more. Down at the Waterside
power station of the New York Edison Company, through their
courtesy, I have had a number of such engines in operation. In
one of them the disks are only nine inches in diameter and the
whole working part is two inches thick. With steam as the
propulsive fluid it develops 110-horse power, and could do
twice as much."

"You have
got what Professor Langley was trying to evolve for his flying
machine -- an engine that will give a horse power for a pound
of weight", I suggested.

**Ten Horse
Power to the Pound. ~**

"I have got
more than that", replied Dr. Tesla. "I have an engine that
will give ten horse power to the pound of weight. That is
twenty-five times as powerful as the lightest weight engine in
use today. The lightest gas engine used on aeroplanes weighs
two and one-half pounds to the horse power. With two and
one-half pounds of weight I can develop twenty-five horse
power."

"That means
the solution of the problem of flying", I suggested.

"Yes, and
many more", was the reply. "The applications of this
principle, both for imparting power to fluids, as in pumps,
and for deriving power from fluids, as in turbine, are
boundless. It costs almost nothing to make, there is nothing
about it to get out of order, it is reversible -- simply have
two ports for the gas or steam, to enter by, one on each side,
and let it into one side or other. There are no blades or
vanes to get out of order -- the steam turbine is a delicate
thing."

I remembered
the bushels of broken blades that were gathered out of the
turbine casings of the first turbine equipped steamship to
cross the ocean, and realized the importance of this phase of
the new engine.

"Then, too",
Dr. Tesla went on, "there are no delicate adjustments to be
made. The distance between the disks is not a matter of
microscopic accuracy and there is no necessity for minute
clearances between the disks and the case. All one needs is
some disks mounted on a shaft, spaced a little distance apart
and cased so that a fluid can enter at one point and go out at
another. If the fluid enters at the centre and goes out at the
periphery it is a pump. If it enters at the periphery and goes
out at the center it is a motor.

"Coupling
these engines in series, one can do away with gearing in
machinery. Factories can be equipped without shafting. The
motor is especially adapted to automobiles, for it will run on
gas explosions as well as on steam. The gas or steam can be
let into a dozen ports all around the rim of the case if
desired. It is possible to run it as a gas engine with a
continuous flow of gas, gasoline and air being mixed and the
continuous combustion causing expansion and pressure to
operate the motor. The expansive power of steam, as well as
its propulsive power, can be utilized as in a turbine or a
reciprocating engine. By permitting the propelling fluid to
move along the lines of least resistance a considerably larger
proportion of the available power is utilized.

"As an air
compressor it is highly efficient. There is a large engine of
this type now in practical operation as an air compressor and
giving remarkable service. Refrigeration on a scale hitherto
never attempted will be practical, through the use of this
engine in compressing air, and the manufacture of liquid air
commercially is now entirely feasible.

"With a
thousand horse power engine, weighing only one hundred pounds,
imagine the possibilities in automobiles, locomotives and
steamships. In the space now occupied by the engines of the
Lusitania twenty-five times her 80,000 horse power could be
developed, were it possible to provide boiler capacity
sufficient to furnish the necessary steam."

"And it
makes the aeroplane practical", I suggested.

"Not the
aeroplane, the flying machine", responded Dr. Tesla. "Now you
have struck the point in which I am most deeply interested --
the object toward which I have been devoting my energies for
more than twenty years -- the dream of my life. It was in
seeking the means of making the perfect flying machine that I
developed this engine.

"Twenty
years ago I believed that I would be the first man to fly;
that I was on the track of accomplishing what no one else was
anywhere near reaching. I was working entirely in electricity
then and did not realize that the gasoline engine was
approaching a perfection that was going to make the aeroplane
feasible. There is nothing new about the aeroplane but its
engine, you know.

"What I was
working on twenty years ago was the wireless transmission of
electric power. My idea was a flying machine propelled by an
electric motor, with power supplied from stations on the
earth. I have not accomplished this as yet, but am confident
that I will in time.

"When I
found that I had been anticipated as to the flying machine, by
men working in a different field, I began to study the problem
from other angles, to regard it as a mechanical rather than an
electrical problem. I felt certain there must be some means of
obtaining power that was better than any now in use. And by
vigorous use of my gray matter for a number of years, I
grasped the possibilities of the principle of the viscosity
and adhesion of fluids and conceived the mechanism of my
engine. Now that I have it, my next step will be the perfect
flying machine."

"An
aeroplane driven by your engine?", I asked.

"Not at
all", said Dr. Tesla. "The aeroplane is fatally defective. It
is merely a toy -- a sporting play-thing. It can never become
commercially practical. It has fatal defects. One is the fact
that when it encounters a downward current of air it is
helpless. The 'hole in the air' of which aviators speak is
simply a downward current, and unless the aeroplane is high
enough above the earth to move laterally but can do nothing
but fall.

"There is no
way of detecting these downward currents, no way of avoiding
them, and therefore the aeroplane must always be subject to
chance and its operator to the risk of fatal accident.
Sportsmen will always take these chances, but as a business
proposition the risk is too great.

"The flying
machine of the future -- my flying machine -- will be heavier
than air, but it will not be an aeroplane. It will have no
wings. It will be substantial, solid, stable. You cannot have
a stable airplane. The gyroscope can never be successfully
applied to the airplane, for it would give a stability that
would result in the machine being torn to pieces by the wind,
just as the unprotected aeroplane on the ground is torn to
pieces by a high wind.

"My flying
machine will have neither wings nor propellers. You might see
it on the ground and you would never guess that it was a
flying machine. Yet it will be able to move at will through
the air in any direction with perfect safety, higher speeds
than have yet been reached, regardless of weather and
oblivious of 'holes in the air' or downward currents. It will
ascend in such currents if desired. It can remain absolutely
stationary in the air, even in a wind, for great length of
time. Its lifting power will not depend upon any such delicate
devices as the bird has to employ, but upon positive
mechanical action."

"You will
get stability through gyroscopes?", I asked.

"Through
gyroscopic action of my engine, assisted by some devices I am
not yet prepared to talk about", he replied.

"Powerful
air currents that may be deflected at will, if produced by
engines and compressors sufficiently light and powerful, might
lift a heavy body off the ground and propel it through the
air", I ventured, wondering if I had grasped the inventor's
secret.

Dr. Tesla
smiled an inscrutable smile.

"All I have
to say on that point is that my airship will have neither gas
bag, wings nor propellers", he said. "It is the child of my
dreams, the product of years of intense and painful toil and
research. I am not going to talk about it any further. But
whatever my airship may be, here at least is an engine that
will do things that no other engine ever has done, and that is
something tangible."

---

***Scientific
American*(30 September 1911), p. 290 ~**
**"From the Complex to the Simple"**

A marked
step was taken in the simplification of prime movers when
Watt's cumbersome beam engine, with its ingenious but
elaborate parallel motion, gave way to the present standard
reciprocating type, with only piston rod, crosshead and
connecting rod interposed between piston and crank. An even
greater advance toward ideal simplicity occurred when, after
years of effort by inventors to produce a practicle rotary,
Parsons brought out his compact, though costly, turbine, in
which the energy of the steam is developed on a zig-zag path
through multitudinous rows of fixed and moving blades.

And now
comes Mr. Tesla with a motor which bids fair to carry the
steam engine another long step toward the ideally simple
prime mover -- a motor in which the fixed and revolving
blades of the turbine give place to a set of steel disks of
simple and cheap construction. If the flow of steam in
spiral curves between the adjoining faces of flat disks is
an efficient method of developing the energy of the steam,
the prime mover would certainly appear to have been at last
reduced to its simplest terms.

The
further development of the unique turbine which we describe
elsewhere will be followed with close attention by the
technical world. The results attained with this small
high-pressure unit are certainly flattering, and give reason
to believe that the addition of a low pressure turbine and a
condenser would make this type of turbine as highly
efficient as it is simple and cheap in construction and
maintenance.

---

***Scientific
American* (30 September 1911), p. 296 ~**
**"The Rotory Heat Motor Reduced to
its Simplest Terms"**

It will
interest the readers of the Scientific American to that
Nikola Tesla, whose reputation must, naturally, stand upon
the contribution he made to electrical engineering when the
art was yet in its comparative infancy, is by training and
choice a mechanical engineer, with a strong leaning to that
branch of it which is covered by the term "steam
engineering". For several years past he has devoted much of
his attention to improvements in thermo-dynamic conversion,
and the result of his theories and practical experiments is
to be found in an entirely new form of prime movers shown in
operation at the waterside station of the New York Edison
Company, who kindly placed the facilities of their great
plant at his disposal for carrying on experimental work.

By the
courtesy of the inventor, we are enabled to publish the
accompanying views, representing the testing plant at the
Waterside station, which are the first photographs of this
interesting motor that have yet been made public.

The basic
principle which determined Tesla's investigations was the
well-known fact that when a fluid (steam, gas or water) is
used as a vehicle of energy, the highest possible economy
can be obtained only when the changes in velocity and
direction of the movement of the fluid are made as gradual
and easy as possible. In the present forms of turbines in
which the energy is transmitted by pressure, reaction or
impact, as in the De Laval, Parsons, and Curtiss types, more
or less sudden changes both of speed and direction are
involved, with consequent shocks, vibration and destructive
eddies. Furthermore, the introduction of pistons, blades,
buckets, and intercepting devices of this general class,
into the path of the fluid involves much delicate and
difficult mechanical construction which adds greatly to the
cost both of production and maintenance.

The
desiderata in an ideal turbine group themselves under the
heads of the theoretical and the mechanical. The
theoretically perfect turbine would be one in which the
fluid was so controlled from the inlet to the exhaust that
its energy was delivered to the driving shaft with the least
possible losses due to the mechanical means employed. The
mechanically perfect turbine would be one which combined
simplicity and cheapness of construction, durability, ease
and rapidity of repairs, and a small ratio of weight and
space occupied to the power delivered on the shaft. Mr.
Tesla maintains that in the turbine which forms the subject
of this article, he has carried the steam and gas motor a
long step forward toward the maximum attainable efficiency,
both theoretical and mechanical. That these claims are well
founded is shown by the fact that in the plant at the Edison
station, he is securing an output of 200 horse-power from a
single-stage steam turbine with atmospheric exhaust,
weighing less than 2 pounds per horse-power, which is
contained within a space measuring 2 feet by 3 feet, by 2
feet in height, and which accomplishes these results with a
thermal fall of only 130 BTU, that is, about one-third of
the total drop available. Furthermore, considered from the
mechanical standpoint, the turbine is astonishingly simple
and economical in construction, and by the very nature of
its construction, should prove to possess such a durability
and freedom from wear and breakdown as to place it, in these
respects, far in advance of any type of steam or gas motor
of the present day.

Briefly
stated, Tesla's steam motor consists of a set of flat steel
disks mounted on a shaft and rotating within a casing, the
steam entering with high velocity at the periphery of the
disks, flowing between them in free spiral paths, and
finally escaping through exhaust ports at their center.
Instead of developing the energy of the steam by pressure,
reaction, or impact, on a series of blades or vanes, Tesla
depends upon the fluid properties of adhesion and viscosity
-- the attraction of the steam to the faces of the disks and
the resistance of its particles to molecular separation
combining in transmitting the velocity energy of the motive
fluid to the plates and the shaft.

By
reference to the accompanying photographs and line drawings,
it will be seen that the turbine has a rotor A which in the
present case consists of 25 flat steel disks, one
thirty-second of an inch in thickness, of hardened and
carefully tempered steel. The rotor as assembled is 3 1/2
inches wide on the face, by 18 inches in diameter, and when
the turbine is running at its maximum working velocity, the
material is never under a tensile stress exceeding 50,000
pounds per square inch. The rotor is mounted in a casing D,
which is provided with two inlet nozzles, B for use in
running direct and B' for reversing. Openings C are cut out
at the central portion of the disks and these communicate
directly with exhaust ports formed in the side of the
casing.

In
operation, the steam, or gas, as the case may be is directed
on the periphery of the disks through the nozzle B (which
may be diverging, straight or converging), where more or
less of its expansive energy is converted into velocity
energy. When the machine is at rest, the radial and
tangential forces due to the pressure and velocity of the
steam cause it to travel in a rather short curved path
toward the central exhaust opening, as indicated by the full
black line in the accompanying diagram; but as the disks
commence to rotate and their speed increases, the steam
travels in spiral paths the length of which increases until,
as in the case of the present turbine, the particles of the
fluid complete a number of turns around the shaft before
reaching the exhaust, covering in the meantime a lineal path
some 12 to 16 feet in length. During its progress from inlet
to exhaust, the velocity and pressure of the steam are
reduced until it leaves the exhaust at 1 or 2 pounds gage
pressure.

The
resistance to the passage of the steam or gas between
adjoining plates is approximately proportionate to the
square of the relative speed, which is at a maximum toward
the center of the disks and is equal to the tangential
velocity of the steam. Hence the resistance to radial escape
is very great, being furthermore enhanced by the centrifugal
force acting outwardly. One of the most desirable elements
in a perfected turbine is that of reversibility, and we are
all familiar with the many and frequently cumbersome means
which have been employed to secure this end. It will be seen
that this turbine is admirably adapted for reversing, since
this effect can be secured by merely closing the right-hand
valve and opening that on the left.

It is
evident that the principles of this turbine are equally
applicable, by slight modifications of design, for its use
as a pump, and we present a photograph of a demonstration
model which is in operation in Mr. Tesla's office. This
little pump, driven by an electric motor of 1/12
horse-power, delivers 40 gallons per minute against a head
of 9 feet. The discharge pipe leads up to a horizontal tube
provided with a wire mesh for screening the water and
checking the eddies. The water falls through a slot in the
bottomof this tube and after passing below a baffle plate
flows in a steady stream about 3/4 inch thick by 18 inches
in width, to a trough from which it returns to the pump.
Pumps of this character show an efficiency favorably
comparing with that of centrifugal pumps and they have the
advantage that great heads are obtainable economically in a
single stage. The runner is mounted in a two-part volute
casing and except for the fact that the place of the
buckets, vanes, etc., of the ordinary centrifugal pump is
taken by a set of disks, the construction is generally
similar to that of pumps of the standard kind.

In
conclusion, it should be noted that although the
experimental plant at the Waterside station develops 200
horse-power with 125 pounds at the supply pipe and free
exhaust, it could show an output of 300 horse-power with the
full pressure of the Edison supply circuit. Furthermore, Mr.
Tesla states that if it were compounded and the exhaust were
led to a low pressure unit, carrying about three times the
number of disks contained in the high pressure element, with
connection to a condenser affording 28-1/2 to 29 inches of
vacuum, the results obtained in the present high-pressure
machine indicate that the compound unit would give an output
of 600 horse-power, without great increase of dimensions.
This estimate is conservative.

The
testing plant consists of two identical turbines connected
by a carefully calibrated torsion spring, the machine to the
left being the driving element, the other the brake. In the
brake element, the steam is delivered to the blades in a
direction opposite to that of the rotation of the disks.
Fastened to the shaft of the brake turbine is a hollow
pulley provided with two diametrically opposite narrow
slots, and an incandescent lamp placed inside close to the
rim. As the pulley rotates, two flashes of light pass out of
the same, and by means of reflecting mirrors and lenses,
they are carried around the plant and fall upon two rotating
glass mirrors placed back to back on the shaft of the
driving turbine so that the center line of the silver
coatings coincides with the axis of the shaft. The mirrors
are so set that when there is no torsion on the spring, the
light beams produce a luminous spot stationary at the zero
of the scale. But as soon as load is put on, the beam is
deflected through an angle which indicates directly the
torsion. The scale and spring are so proportioned and
adjusted that the horse-power can be read directly from the
deflections noted. The indications of this device are very
accurate and have shown that when the turbine is running at
9,000 revolutions under an inlet pressure of 125 pounds to
the square inch, and with free exhaust, 200 brake
horse-power are developed. The consumption under these
conditions of maximum output is 38 pounds of saturated steam
per horse-power per hour -- a very high efficiency when we
consider that the heat-drop, measured by thermometers, is
only 130 BTU, and that the energy transformation is effected
in one stage. Since about three times this number of heat
units are available in a modern plant with super-heat and
high vacuum, the above means a consumption of less than 12
pounds per horse-power hour in such turbines adapted to take
up the full drop. Under certain conditions, however, very
high thermal efficiencies have been obtained which
demonstrate that in large machines based on this principle,
in which a very small slip can be secured, the steam
consumption will be much lower and should, Mr. Tesla states,
approximate the theoretical minimum, thus resulting in
nearly frictionless turbine transmitting almost the entire
expansive energy of the steam to the shaft.

---

***Popular
Mechanics Magazine* (December 1911)**
**"The Tesla Turbine"**

**E. F. Stearns**

Engineers
and men of science throughout the world are awaiting with
unusual interest the completion of tests of a new steam
turbine designed by Nikola Tesla, which preliminary
experiments indicate will give enormous power from a
comparatively small and extremely lightweight engine. Ten
horsepower to a pound of weight has already been developed
with the engines that have been tested and enthusiasts who
have witnessed the work of the turbine declare the perfect
rotor has at last been found. To what extent this is true,
time and the construction of larger units than have yet been
used must prove. At present, while the practical
experimental stage has not yet been passed, the entire
engineering world is profoundly interested in the work that
has been done, and awaits future development with much
concern.

Operation
of the Tesla engine depends upon two well-known properties
of fluids: adhesion -- the tendency, for example, of a
certain amount of water to cling to a smooth metal surface,
even when the bulk of the water has been shaken off; and
viscosity, the resistance of fluids to molecular separation,
the tendency of one drop, in a mass of fluid, to drag
adjoining drops with it, if set in motion.

In its
simplest form, the new idea takes the shape of the
inventor's little "air-diffuser". This consists of half a
dozen very thin steel disks, some 9 or 10 in. in diameter,
set horizontally, about 1/8 in. apart, on the upright shaft
of a small, horizontal electric motor, the center of each
disk being cut away in a 3-in. circle. With current switched
into the motor, the disks revolve, and instantly strong
suction can be felt by the hand held several inches above
the axis, while a powerful current of air is blown from the
spaces between the disks. The air, in short, is being sucked
into the central opening and hurled out at the periphery.
Consider now that disks and shaft have been inclosed in an
air-tight case, with an inlet at the axis and an outlet at
one point of the periphery; we have an air pump, a Tesla
blower, one of which, now in operation, is delivering 10,000
cu. ft. of air per minute.

Suppose
again that water, instead of air, be the fluid admitted.
Entering the cut-away space at the centers of the disks, the
adhesion of the metal drags it, in a widening spiral, toward
the spinning circumferences, there to hurl it away in a
tangential direction; and since the water must now leave the
case by its one outlet, we have the Tesla pump, on rather
new lines.

Assume
that the pumping process is to be reversed, that the disks,
instead of being turned by an outside force, are to produce
power themselves, that steam under pressure has been
substituted for the water. The steam, admitted to the case,
strikes the edges of the disks and takes the path of least
resistance between them, a narrowing spiral toward the
outlet through their centers. The disks themselves are
dragged around, the shaft is turned and power is being
generated in an entirely new fashion.

Working
under the best conditions -- in the experimental laboratory
a single disk of 9 3/4 in. diameter, with a center outlet of
3 5/8 in., will develop 5 hp. Without nearly approaching the
limit of strain of the materials, the pressure could be
increased so that the velocity of rotation would be doubled
and the power quadrupled; so that with a single steel plate,
1/32 in. in thickness, weighing about 3/8 lb., and
delivering 20 hp, we have a possible 53 hp. to 1 lb. of
actually working material. Or a more concrete example can be
found in a double Tesla turbine, built for practical service
and nearly completed. In this there are two sets of disks,
arranged to revolve in opposite directions and each set
developing 200 hp.

A little
model pump in which five disks, 3 in. in diameter, contained
in the lower front, circular case, throw 40 gal. a minute
when the little electric motor is started up. The water
flows out of a slit at the bottom of the upper pipe and
flows back to the lower tank as seen in the foreground. This
model illustrates one point astonishingly: the power can be
shut off when the pump is in full operation and everything
stops instantly without the slightest jar. With the power
switched on suddenly, the full flow is resumed so quickly
that the interval between the click of the switch and the
full stream of water is too small to be determined with an
ordinary watch.

**Complete
System:**

![](popmech1.jpg)

**Casing Removed to Show Disks:**

![](popmech2.jpg)

**Fountain:**

![](popmech3.jpg)

---

**US Patent # 1,061,142**

**"Fluid Propulsion"**

**Nikola Tesla**

Be it known
that I, Nikola Tesla, and engineer residing at the Waldorf
Astoria, corner Fifth Avenue and Thirty Fourth Street, in the
Borough of Manhattan, City and State of New York, United
States of America, having invented certain new and useful
improvements in fluid propulsion, do hereby declare the
following is a full, clear and exact description of the same.

In the
practical application of mechanical power based on the use of
a fluid as vehicle of energy it has been demonstrated that, in
order to attain the highest economy, the changes in velocity
and direction of movement of the fluid should be as gradual as
possible. In the present forms of such apparatus more or less
sudden changes, shocks and vibrations are unavoidable. Besides
the employment of the usual devices for imparting to vanes and
blades, necessarily introduce numerous defects and limitations
and adds to the complication, cost of production and
maintenance of the machine.

The object
of my invention is to overcome these deficiencies and to
effect the transmission and transformation of mechanical
energy through the agency of fluids in a more perfect manner,
and by means simpler and more economical than those heretofore
employed.

I accomplish
this by causing the propelled or propelling fluid to move in
natural paths or stream lines of least resistance, free from
constraint and disturbance such as occasioned by vanes or
kindred devices, and to change its velocity and direction of
movement by imperceptible degrees, thus avoiding the losses
due to sudden variations while the fluid is receiving or
imparting energy.

It is well
know that a fluid possesses among others, two salient
properties: adhesion and viscosity. Owing to these a body
propelled through such a medium encounters a peculiar
impediment known as "lateral" or "skin resistance", which is
two-fold: one arising from the shock of the fluid against the
asperities of the solid substance, the other from internal
forces opposing molecular separation. As an inevitable
consequence a certain amount of the fluid is dragged along by
the moving body. Conversely, if the body were placed in a
fluid in motion, for the same reasons, it is impelled in the
direction of the movement.

These
effects, in themselves, are of daily observation, but I
believe that I am the first to apply them in a practical and
economical matter of fluid propulsion. The nature of my
discovery and the principles of construction of the apparatus,
which I have designed for carrying it out, I shall now proceed
to describe by reference to the accompanying drawings which
illustrate an operative and efficient embodiment of the same.

**Figure 1**
is a partial end view, and

![](61142a.jpg)

**Figure 2**
a vertical cross section of a pump or compressor, which
Figures 3 and 4 represent, respectively, in corresponding
views, a rotary engine or turbine, both machines being
constructed and adapted to be operated in accordance with my
invention.

In these
drawings the device illustrated contains a runner composed of
a plurality of flat rigid disks 1 of a suitable diameter,
keyed to a shaft 2, and held in a position by a threaded nut
3, a shoulder 4 and washers 5 of the requisite thickness. Each
disk has a number of central openings 6, the solid portions
between which form spokes 7, preferably curved, as shown, for
the purpose of reducing the loss of energy due to the impact
of the fluid. The runner is mounted in a two-part volute
casing 8 having stuffing boxes 9 and inlets 10 leading to its
central portion. In addition a gradually widening and rounded
outlet 11 is provided formed with a flange, for connection to
a pipe as usual. The casing 8 rests upon a base 12 shown only
in part and supporting the bearings for the shaft 2, which
being of ordinary construction, are omitted from the drawings.

An
understanding of the principle embodied in this device will be
gained from the following description of its mode of
operation. Power being applied to the shaft and the runner set
in rotation in the direction of the solid arrow, the fluid by
reason of its properties of adherence and viscosity, upon
entering through the inlets 10 and coming in contact with the
disks 1 is taken hold of by the same and subjected to two
forces, one acting tangentially in the direction of rotation,
and the other radiates outward. The combined effect of the
tangential and centrifugal forces is to propel the fluid with
continuously increasing velocity in a spiral path until it
reaches the outlet 11 from which it is ejected. This spiral
movement, free and undisturbed and essentially dependent on
these properties of the fluid, permitting it to adjust itself
to natural paths or streamlines and to change its velocity and
direction by insensible degrees, is characteristic of this
method of propulsion and advantageous in its application.
While traversing the chamber enclosing the runner, the
particles of the fluid may complete one or more turns, or but
part of one turn. In any given case their path can be closely
calculated and graphically represented, but fairly accurate
estimates of turns can be obtained simply by determining the
number of revolutions required to renew the fluid passing
through the chamber and multiplying it by the ratio between
the mean speed of the fluid and that of the disks. I have
found that the quantity of fluid propelled in this manner is,
other conditions being equal, approximately proportionate to
the active surface of the runner and to its effective speed.
For this reason, their performance of such machines augments
at an exceedingly high rate with the increase of their size
and speed of revolution.

The
dimensions of the device as a whole, and the spacing of the
disks in any given machine will be determined by the
conditions and requirements of special cases. It may be stated
that the intervening distance should be the greater, the
larger the diameter of the disks, the longer the spiral path
of the fluid and the greater its viscosity. In general, the
spacing should be such that the entire mass of the fluid,
before leaving the runner, is accelerated to a nearly uniform
velocity, not much below that of the periphery of the disks
under normal working conditions and almost equal to it when
the outlet is closed and the particles move in concentric
circles.

It may also
be pointed out that such a pump can be made without openings
and spokes in the runner, as by using one or more solid disks,
each in its own casing, in which form the machine will be
eminently adapted for sewage, dredging and the like, when the
water is charged with foreign bodies and spokes or vanes
especially objectionable.

Another
application of this principle which I have discovered to be
not only feasible, buy thoroughly practicable and efficient,
is the utilization of machines such as above described for the
compression or rarefaction of air, or gases in general. In
such cases it will be found that most of the general
considerations obtaining in the case of liquids, properly
interpreted, hold true. When, irrespective of the character of
the fluid, considerable pressure are desired, staging or
compounding may be resorted to in the usual way, the
individual runners being, preferably, mounted on the same
shaft. It should be added that the same end may be attained
with one single runner by suitable deflection of the fluid
through rotational or stationary passages.

The
principles underlying the invention are capable of embodiment
also in that field of mechanical engineering which is
concerned in the use of fluids as motive agents, for while in
some respects the actions in the latter case are directly
opposite to those met with in the propulsion of fluids, the
fundamental laws applicable in the two case are the same. In
other words, the operation described above is reversible, for,
if water or air, under pressure, be admitted to the opening 11
the runner is set in rotation in the direction of the dotted
arrow by reason of the peculiar properties of the fluid,
which, traveling in a spiral path, and with continuously
diminishing velocity, reaches the orifices 6 and 10 through
which it is discharged.

When
apparatus of the general character described is employed for
the transmission of power, however, certain departures from
similarity between transmitter and receiver may be necessary
for securing the best results. I have, therefore, included
that part of my invention which is directly applicable to the
use of fluids as motive agents in a separate application filed
January 17, 1911, Serial No. 603,049. It may be here pointed
out, however, as is evident from the above considerations,
that when transmitting power from one shaft to another by such
machines, any desired ratio between the speeds of rotation may
be obtained by proper selection of the diameters of the disks,
or, by suitably staging the transmitter, the receiver, or
both. But it may be pointed out that in one respect, at least,
the two machines are essentially different

In the pump,
the radial or static pressure, due to centrifugal force, is
added to the tangential or dynamic, thus increasing the
effective head and assisting in the expulsion of the fluid. In
the motor, on the contrary, the first named pressure being
opposed to that of supply reduces the effective head and the
velocity of radial flow towards the center. Again, in the
propelled machine, a great torque is always desirable, this
calling for an increased number of disks and smaller distance
of separation, while in the propelling machine, for numerous
economic reasons, the rotary effect should be the smallest and
the speed the greatest practicable. Many other considerations,
the design and construction, but the preceding is thought to
contain all necessary information in this regard.

It will be
understood that the principles of construction and operation
above generally set forth, are capable of embodiment in
machines of the most widely different forms, and adapted for
the greatest variety of purposes. In my present application, I
have sought to describe and explain only the general and
typical applications of the principle, which I believe I am
the first to realize and turn to useful account.

---

**US Patent # 1,061,206**

**(6 May 1913)**

**"Turbine"**

**Nikola Tesla**

Be it known
that I, Nikola Tesla, a citizen of the United States, residing
at New York, in the county and State of New York, have
invented certain new and useful Improvements in Rotary Engines
and Turbines, of which the following is a full, clear, and
exact description.

In the
practical application of mechanical power, based on the use of
fluid as the vehicle of energy, it has been demonstrated that,
in order to attain the highest economy, the changes in the
velocity and direction of movement of the fluid should be as
gradual as possible. In the forms of apparatus heretofore
devised or proposed, more or less sudden changes, shocks, and
vibration are unavoidable. Besides, the employment of the
usual deices for imparting to, or deriving energy from a
fluid, such as pistons, paddles, vanes, and blades,
necessarily introduces numerous defects and limitations and
adds to the complication, cost of production and maintenance
of the machines.

The object
of my invention is to overcome these deficiencies and to
effect the transmission and transformation of mechanical
energy through the agency of fluids in a more perfect manner
and by means simpler and more economical than those heretofore
employed. I accomplish this by causing the propelling fluid to
move in natural paths or stream lines of least resistance,
free from constraint and disturbance such as occasioned by
vanes or kindred devices, and to change its velocity and
direction of movement by imperceptible degrees, thus avoiding
the losses due to sudden variation while the fluid is
imparting energy.

It is well
known that a fluid possesses, among others, two salient
properties, adhesion and viscosity. Owing to these a solid
body propelled through such a medium encounters a peculiar
impediment known as "lateral" or skin resistance, which is
twofold, one arising from the shock of the fluid against the
asperities of the solid substance, the other from internal
forces opposing molecular separation. As an inevitable
consequence a certain amount of the fluid is dragged along by
the moving body. Conversely, if the body be placed in a fluid
in motion, for the same reasons, it is impelled in the
direction of movement. These effects, in themselves, are of
daily observation, but I believe that I am the first to apply
them in a practical and economical manner in the propulsion of
fluids or in their use as motive agents.

In an
application filed by me October 21st, 1909, Serial Number
523,832 of which this case is a division, I have illustrated
the principles underlying my discovery as embodied in
apparatus designed for the propulsion of fluids. The same
principles, however, are capable of embodiment also in that
field of mechanical engineering which is concerned in the use
of fluids as motive agents, for while in certain respects the
operations in the latter case are directly opposite to those
met with in the propulsion of fluids, and the means employed
may differ in some features, the fundamental laws applicable
in the two cases are the same. In other words, the operation
is reversible, for if water or air under pressure be admitted
to the opening constituting the outlet of a pump or blower as
described, the runner is set in rotation by reason of the
peculiar properties of the fluid which, in its movement
through the device, imparts its energy thereto.

The present
application, which is a division of that referred to, is
specially intended to describe and claim my dsicovery above
set forth, so far as it bears on the use of fluids as motive
agents, as distinguished from the applications of the same to
the propulsion or compression of fluids.

In the
drawings, therefore, I have illustrated only the form of
apparatus designed for the thermo-dynamic conversion of
energy, a field in which the applications of the principle
have the greatest practical value.

**Figure 1**
is a partial end view, and

![](61206-1.jpg)

**Figure 2**
a vertical cross-section of a rotary engine or turbine,
constructed and adapted to be operated in accordance with the
principles of my invention.

![](61206-2.jpg)

The
apparatus comprises a runner composed of a plurality of flat
rigid disks 13 of suitable diameter, keyed to a shaft 16, and
held in position thereon by a threaded nut 11, a shoulder 12,
and intermediate washers 17. The disks have openings 14,
adjacent to the shaft and spokes 15, which may be
substantially straight. For the sake of clearness, but a few
disks, with comparatively wide intervening spaces, are
illustrated.

The runner
is mounted in a casing comprising two end castings 19, which
contain the bearings for the shaft 16, indicated but not shown
in detail; stuffing boxes 21 and outlets 20. The end castings
are united by a central ring 22, which is bored out to a
circle of slightly larger diameter than that of the disks, and
has flanged extensions 23, and inlets 24, into which finished
ports or nozzles 25 are inserted. Circular grooves 26 and
labyrinth packing 27 are provided on the sides of the runner.
Supply pipes 28, with valves 29, are connected to the flanged
extensions of the central ring, one of the valves being
normally closed.

For a more
ready and complete understanding of the principle of operation
it is of advantage to consider first the actions that take
place when the device is used for the propulsion of fluids for
which purpose let it be assumed that power is applied to the
shaft and the runner set in rotation say in a clockwise
direction. Neglecting, for the moment, those features of
construction that make for or against the efficiency of the
device as a pump, as distinguished from a motor, a fluid, by
reason of its properties of adherence and viscosity, upon
entering through the inlets 20, and coming in contact with the
disks 13, is taken hold of by the latter and subjected to two
forces, one acting tangentially in the direction of rotation,
and the other radially outward. The combined effect of these
tangential and centrifugal forces is to propel the fluid with
continuously increasing velocity in a spiral path until it
reaches a suitable peripheral outlet from which it is ejected.
This spiral movement, free and undisturbed and essentially
dependant on the properties of the fluid, permitting it to
adjust itself to natural paths or stream lines and to change
its velocity and direction by insensible degrees, is a
characteristic and essential feature of this principle of
operation.

While
traversing the chamber inclosing the runner, the particles of
the fluid may complete one or more turns, or but a part of one
turn, the path followed being capable of close calculation and
graphic representation, but fairly accurate estimates of turns
can be obtained simply by determining the number of
revolutions required to renew the fluid passing through the
chamber and multiplying it by the ratio between the mean speed
of the fluid and that of the disks. I have found that the
quantity of fluid propelled in this manner is, other
conditions being equal, approximately proportionate to the
active surface of the runner and to its effective speed. For
this reason, the performance of such machines augments at an
exceedingly high rate with the increase of their size and
speed of revolution.

The
dimensions of the device as a whole, and the spacing of the
disks in any given machine will be determined by the
conditions and requirements of special cases. It may be stated
that the intervening distance should be the greater, the
larger the diameter of the disks, the longer the spiral path
of the fluid and the greater its viscosity. In general, the
spacing should be such that the entire mass of the fluid,
before leaving the runner, is accelerated to a nearly uniform
velocity, not much below that of the periphery of the disks
under normal working conditions, and almost equal to it when
the outlet is closed and the particles move in concentric
circles.

Considering
now the converse of the above described operation and assuming
that fluid under pressure be allowed to pass through the valve
at the side of the solid arrow, the runner will be set in
rotation in a clockwise direction, the fluid traveling in a
spiral path and with continuously diminishing velocity until
it reaches the orifices 14 and 20, through which it is
discharged. If the runner be allowed to turn freely, in nearly
frictionless bearings, its rim will attain a speed closely
approximating the maximum of that of the adjacent fluid and
the spiral path of the particles will be comparatively long,
consisting of many almost circular turns. If load is put on
and the runner slowed down, the motion of the fluid is
retarded, the turns are reduced, and the path is shortened.

Owing to a
number of causes affecting the performance, it is difficult to
frame a precise rule which would be generally applicable, but
it may be stated that within certain limits, and other
conditions being the same, the torque is directly
proportionate to the square of the velocity of the fluid
relatively to the runner, and to the effective area of the
disks, and inversely, to the distance separating them. The
machine will, generally, perform its maximum work when the
effective speed of the runner is one-half that of the fluid;
but to attain the highest economy, the relative speed or slip,
for any given performance, should be as small as possible.
This condition may be to any desired degree approximated by
increasing the active area of and reducing the space between
the disks.

When
apparatus of the kind described is employed for the
transmission of power certain departures from similarity
between transmitter and receiver are necessary for securing
the best results. It is evident that when transmitting power
from one shaft to another by such machines, any desired ratio
between the speeds of rotation may be obtained by a proper
selection of the diameters of the disks, or by suitably
staging the transmitter, the receiver, or both. But it may be
pointed out that in one respect, at least, the two machines
are essentially different. In the pump, the radial or static
pressure, due to centrifugal force, is added to the tangential
or dynamic, thus increasing the effective head and assisting
in the expulsion of the fluid. In the motor, on the contrary,
the first named pressure, being opposed to that of supply,
reduces the effective head and the velocity of radial flow
toward the center. Again, in the propelled machine a great
torque is always desirable, this calling for an increased
number of disks and smaller distance of separation, while in
the propelling machine, for numerous economic reasons, the
rotary effort should be the smallest and the speed the
greatest practicable. Many other considerations, which will
naturally suggest themselves, may affect the design and
construction, but the preceding is thought to contain all
necessary information in this regard.

In order to
bring out a distinctive feature, assume, in the first place,
that the motive medium is admitted to the disk chamber through
a port, that is a channel which it traverses with nearly
uniform velocity. In this case, the machine will operate as a
rotary engine, the fluid continuously expanding on its
tortuous path to the central outlet. The expansion takes place
chiefly along the spiral path, for the spread inward is
opposed by the centrifugal force due to the velocity of the
whirl and by the great resistance to radial exhaust. It is to
be observed that the resistance to the passage of the fluid
between the plates is, approximately, proportionate to the
square of the relative speed, which is maximum in the
direction toward the center and equal to the full tangential
velocity of the fluid. The path of least resistance,
necessarily taken in obedience to a universal law of motion
is, virtually, also that of least relative velocity. Next,
assume that the fluid is admitted to the disk chamber not
through a port, but a diverging nozzle, a device converting
wholly or in part, the expansive into velocity-energy. The
machine will then work rather like a turbine, absorbing the
energy of kinetic momentum of the particles as they whirl,
with continuously decreasing speed, to the exhaust.

The above
description of the operation, I may add, is suggested by
experience and observation, and is advanced merely for the
purpose of explanation. The undeniable fact is that the
machine does operate, both expansively and impulsively. When
the expansion in the nozzles is complete, or nearly so, the
fluid pressure in the peripheral clearance space is small; as
the nozzle is made less divergent and its section enlarged,
the pressure rises, finally approximating that of the supply.
But the transition from purely impulsive to expansive action
may not be continuous throughout, on account of critical
states and conditions and comparatively great variations of
pressure may be caused by small changes of nozzle velocity.

In the
preceding it has been assumed that the pressure of supply is
constant or continuous, but it will be understood that the
operation will be, essentially the same if the pressure be
fluctuating or intermittent, as that due to explosions
occurring in more or less rapid succession.

A very
desirable feature, characteristic of machines constructed and
operated in accordance with this invention, is their
capability of reversal of rotation. Fig 1, while illustrative
of a special case, may be regarded as typical in this respect.
If the right had valve be shut off and the fluid is rotated in
the direction of the dotted arrow, the operation, and also the
performance remaining the same as before, the central ring
being bored to a circle with this purpose in view. The same
result may be obtained in many other ways by specially
designed valves, ports, or nozzles for reversing the flow, in
the description of which is omitted here in the interest of
simplicity and clearness. For the same reasons but one
operative port or nozzle is illustrated which might be adapted
to a volute but does not fit best a circular bore. It will be
understood that a number of suitable inlets may be provided
around the periphery of the runner to improve the action and
that the construction of the machine may be modified in many
ways.

Still
another valuable and probably as unique quality of such motors
or prime movers may be described. By proper construction and
observance of working conditions the centrifugal pressure,
opposing the passage of the fluid, may, as already indicated,
be made nearly equal to the pressure of supply when the
machine is running idle. If the inlet section be large, small
changes in the speed of revolution will produce great
differences in flow which are further enhanced by the
concomitant variations in the length of the spiral path. A
self regulating machine is thus obtained bearing a striking
resemblance to a direct-current electric motor in this respect
that, with great differences of impressed pressure in a wide
open channel the flow of the fluid through the same is
prevented by virtue of rotation. Since the centrifugal head
increases as the square of the revolutions, or even more
rapidly, and with modern high grade steel great peripheral
velocities are practical, it is possible to attain that
condition in a single stage machine, more readily if the
runner be of large diameter. Obviously this problem is
facilitated by compounding, as will be understood by those
skilled in the art. Irrespective of its bearing on economy,
this dependency which is, to a degree, common to motors of the
above description, is of special advantage in the operation of
large units, as it affords a safeguard against running away
and destruction. Besides these, such a prime mover possesses
many other advantages, both constructive and operative. It is
simple, light, and compact, subject to but little wear, cheap
and exceptionally easy to manufacture as small clearances and
accurate milling work are not essential to good performance.
In operation it is reliable, there being no valves, sliding
contacts or troublesome varies. It is almost free of windage,
largely independent of nozzle efficiency and suitable for high
as well as for low fluid velocities and speeds of revolution.

It will be
understood that the principles of construction and operation
above generally set forth, are capable of embodiment in
machines of the most widely different forms, and adapted for
the greatest variety of purposes. In my present specification
I have sought to describe and explain only the general and
typical applications of the principle which I believe I am the
first to realize and turn to useful account.

---

**US Patent #
1,329,559**

**(3 February 1920)**

**"Valvular Conduit"**

**Nikola Tesla**

Be it known
that I, Nikola Tesla, have invented certain new and useful
Improvements in Valvular Conduits, of which the following is a
full, clear and exact description.

In most of
the machinery universally employed for the development,
transmission and transformation of mechanical energy, fluid
impulses are made to pass, more or less freely, through
suitable channels or conduits in one direction while their
return is effectively checked or entirely prevented. This
function is generally performed by devices designated as
valves, comprising carefully fitted members the precise
relative movements of which are essential to the efficient and
reliable operation of the apparatus. The necessity of, and
absolute dependence on these, limits the machine in many
respects, detracting from its practical value and adding
greatly to the cost of manufacture and maintenance. As a rule
the valve is a delicate contrivance, very liable to wear and
get out of order and thereby imperil ponderous, complex and
costly mechanisms and, moreover, it fails to meet the
requirements when the impulses are extremely sudden or rapid
in succession and the fluid is highly heated or corrosive.

Though these
and other correlated facts were known to the very earliest
pioneers in the science and art of mechanics, no remedy has as
yet been found or proposed to date so far as I am aware and I
believe that I am the first to discover or invent any means,
which permit the performance of the above function without the
use of moving parts, and which permit the performance of the
above function without the use of moving parts, and which it
is the object of this application to describe.

Briefly
expressed, the advance I have achieved consists in the
employment of a peculiar channel or conduit characterized by
valvular action.

The
invention can be embodied in many constructions greatly varied
in detail, but for the explanation of the underlying principle
it may be broadly stated that the interior of the conduit is
provided with enlargements, recesses, projections, baffles or
buckets which, while offering virtually no resistance to the
passage of the fluid in one direction, other than surface
friction, constitute an almost impassable barrier to its flow
in the opposite sense by reason of the more or less sudden
expansions, contractions, deflections, reversals of direction,
stops and starts and attendant rapidly succeeding
transformations of the pressure and velocity energies.

For the full
and complete disclosure of the device and of its mode of
action reference is made to the accompanying drawings in
which: --

**Figure 1**
is a horizontal projection of such a valvular conduit with the
top plate removed.

![](valv12.jpg)

**Figure 2**
is a side view of the same in elevation.

**Figure 3**
is a diagram illustrative of the application of the device to
a fluid propelling machine such as a reciprocating pump or
compressor, and

![](valv3.jpg)

**Figure 4**
is a plan showing the manner in which the invention is, or may
be used, to operate a fluid propelled rotary engine or
turbine.

![](valv4.jpg)

Referring to
Figure 1, 1 is a casing of metal or other suitable material
which may be cast, milled or pressed from sheet in the desired
form. From its side walls extend alternatively projections
terminating in buckets 2 which, to facilitate manufacture are
congruent and spaced at equal distances, but need not be. In
addition to these there are independent partitions 3 which are
deemed of advantage and the purpose of which will be made
clear. Nipples 4 and 5, one at each end, are provided for pipe
connection. The bottom is solid and the upper or open side is
closed by a fitting plate 6 as shown in Figure 2. When desired
any number of such pieces may be joined in series, thus making
up a valvular conduit of such length as the circumstances may
require.

In
elucidation of the mode of operation let it be assumed that
the medium under pressure be admitted at 5. Evidently, its
approximate path will be as indicated by the dotted line 7,
which is nearly straight, that is to say, if the channel be of
adequate cross-section, the fluid will encounter a very small
resistance and pass through freely and undisturbed, at least
to a degree. Not so if the entrance be at the opposite end 4.
In this case the flow will not be smooth and continuous, but
intermittent, the fluid being quickly deflected and reversed
in direction, set in swirling motion, brought to rest and
again accelerated, these processes following one another in
rapid succession. The partitions 3 serve to direct the stream
upon the buckets and to intensify the actions causing violent
surges and eddies which interfere very materially with the
flow through the conduit. It will be readily observed that the
resistance offered to the passage of the medium will be
considerable even if it be under constant pressure, but the
impediments will be of full effect only when it is supplied in
pulses and, more especially, when the same are extremely
sudden and of high frequency. In order to bring the fluid
masses to rest and to high velocity in short intervals of time
energy must be furnished at a rate which is unattainable, the
result being that the impulse cannot penetrate very far before
it subsides and gives rise to movement in the opposite
direction. The device not only acts as a hinderment to the
bodily return of particles but also, in a measure, as a check
to the propagation of a disturbance through the medium. Its
efficacy is chiefly determined; first, by the magnitude of the
ratio of the two resistances offered to disturbed and
undisturbed flow, respectively, in the directions from 4 to 5
and from 5 to 4, in each individual element of the conduit;
second, by the number of complete cycles of action taking
place in a given length of the valvular channel and third, by
the character of the impulses themselves. A fair idea may be
gained from simple theoretical considerations.

Examining
more closely the mode of operation it will be seen that, in
passing from one to the next bucket, in the direction of
disturbed flow, the fluid undergoes two complete reversals or
deflections through 180 deg while it suffers only two small
deviation from about 10 deg to 20 deg when moving in the opposite
sense. In each case the loss of head will be proportionate to
a hydraulic coefficient dependent on the angle of deflection
from which it follows that, for the same velocity, the ratio
of the two resistances will be as that of the two
coefficients. The theoretical value of this ratio may be 200
or more, but it must be taken as appreciable less although
surface friction too is greater in the direction of disturbed
flow. In order to keep it as large as possible, sharp bends
should be avoided, for these will add to both resistance and
reduce the efficiency. Whenever practicable, the piece should
be straight; the next best is the circular form.

That the
peculiar function of such a conduit is enhanced by increasing
the number of bucket or elements and, consequently, cyclic
processes in a given length is an obvious conclusion, but
there is no direct proportionality, because the successive
actions diminish in intensity. Definite limits, however, are
set constructively and otherwise to the number of elements per
unit length of the channel, and the most economical design can
only be evolved through long experience.

Quite apart
from any mechanical features of the device the character of
the impulses has a decided influence on its performance and
the best results will be secured, when there are produced at
4, sudden variations of pressure in relatively long intervals,
while a constant pressure is maintained at 5. Such is the case
in one of its most valuable industrial applications which will
be specifically described.

In order to
conduce to a better understanding, reference may first be made
to Figure 3 which illustrates another special use and in which
8 is a piston fixed to a shaft 9 and fitting freely in a
cylinder 10. The latter is closed at both ends by flanged
heads 11 and 12 having sleeves or stuffing boxes 13 and 14 for
the shaft. Connection between the two compartments, 15 and 16,
of the cylinder is established through a valvular conduit and
each of the heads is similarly equipped. For the sake of
simplicity these devices are diagrammatically shown, the solid
arrows indicating the direction of undisturbed flow. An
extension of the shaft 9 carries a second piston 17 accurately
ground to and sliding easily in a cylinder 18 closed at the
ends by plates and sleeves as usual. Both piston and cylinder
are provided with inlet and outlet ports marked, respectively,
19 and 20. This arrangement is familiar, being representative
of a prime mover of my invention, termed "mechanical
oscillator", with which it is practicable to vibrate a system
of considerable weight many thousand times per minute.

Suppose now
that such rapid oscillations are imparted by this or other
means to the piston 8. Bearing in mind the preceeding, the
operation of the apparatus will be understood at a glance.
While moving in the direction of the solid arrow, from 12 to
11, the piston 8 will compress the air or other medium in the
compartment 16 and expel it from the same, respectively, as
closed and open valves. During the movement of the piston in
the opposite direction, from 11 to12, the medium which has
meanwhile filled the chamber 15 will be transferred to
compartment 16, egress being prevented by the device in head
12 and that in the piston allowing free passage. These
processes will be repeated in very quick succession. If the
nipples 4 and 5 are put in communication with independent
reservoirs, the oscillations of the piston 8 will result in a
compression of air at 4 and rarefaction of the same at 5.
Obviously, the Valvular channels being turned the other way,
as indicated by dotted lines in the lower part of the figure,
the opposite will take place. The devices in the piston have
been shown merely by way of suggestion and can be dispensed
with. Each of the chambers 15 and 16 being connected to two
conduits as illustrated, the vibrations of a solid piston as 8
will have the same effect and the machine will then be a
double acting pump or compressor. It is likewise unessential
that the medium be admitted to the cylinder through such
devices for in certain instances ports, alternately closed and
opened by the piston, may serve the purpose. As a matter of
course, this novel method of propelling fluids can be extended
to multistage working in which case a number of pistons will
be employed, preferably on the same shaft and of different
diameters in conformity with well established principles of
mechanical design. In this way any desired ratio of
compression or degree of rarefaction may be attained.

Figure 4
exemplifies a particularly valuable application of the
invention to which reference has been made above. The drawing
shows in vertical cross section a turbine which may be of any
type but is in this instance one invented and described by me
and supposed to be familiar to engineers. Suffice it to state
that the rotor 21 of the same is composed of flat plates which
are set in motion through the adhesive and viscous action of
the working fluid, entering the system tangentially at the
periphery and leaving it at the center. Such a machine is a
thermodynamic transformer of an activity surpassing by far
that of any other prime mover, it being demonstrated in
practice that each single disk of the rotor is capable of
performing as much work as a whole bucketwheel. Besides, a
number of other advantages, equally important, make it
especially adapted for operation as an internal combustion
motor. This may be done in many ways, but the simplest and
most direct plan of which I am aware is the one illustrated
here. Referring again to the drawing, the upper part of the
turbine casing 22 has bolted to it a separate casing 23, the
central cavity 24 of which forms the combustion chamber. To
prevent injusry through excessive heating a jacket 25 may be
used, or else water injected, and when these means are
objectionable recourse may be had to air cooling, this all the
more rapidly as very high temperatures are practicable. The
top of casting 23 is closed by a plate 20 with a sparking or
hot wire plug 27 and in its sides are screwed two Valvular
conduits communicating with the central chamber 24. One of
these is, normally, open to the atmosphere while the other
connects to a source of fuel supply as a gas main 28. The
bottom of the combustion chamber terminates in a suitable
nozzle 29 which consists of separate pieces of heat resisting
material. To regulate the influx of the explosion constituents
and secure the proper mixture of air and gas conduits are
equipped, respectively, with valves 30and 31. The exhaust
openings 82 of the rotor should be in communication with a
ventilator, preferably carried on the same shaft and of any
suitable construction. Its use, however, while advantageous,
is not indispensable, the suction produced by the turbine
rotor itself being, in some cases at least, sufficient to
insure proper working. This detail is omitted from the drawing
as unessential to the understanding.

But a few
words will be needed to make clear the mode of operation. The
air valve 30 being open, and sparking established across
terminals 27, the gas is turned on slowly until the mixture in
the chamber 24 reaches the critical state and is ignited. Both
the conduits behaving, with respect to efflux, as closed
valves, the products of combustion rush out through the nozzle
29 acquiring still greater velocity by expansion and,
imparting their momentum to the rotor 21, start it from rest.
Upon the subsidence of the explosion the pressure in the
chamber sinks below the atmospheric owing to the pumping
action of the rotor or ventilator and new air and gas is
permitted to enter, cleaning the cavity and channels and
making up a fresh mixture which is detonated as before, and so
on, the successive impulses of the working fluid producing an
almost continuous rotary effort. After a short lapse of time
the chamber becomes heated to such a degree that the ignition
device may be shut off without disturbing the established
regime. This manner of starting the turbine involves the
employment of an unduly large combustion chamber which is not
commendable from the economic point of view, for not only does
it entail increased heat losses but the explosions cannot be
made to follow one another with such rapidity as would be
desirable to insure the best Valvular action. When the chamber
is small an auxiliary means for starting, as compressed air,
may be resorted to and a very quick succession of explosions
can then be obtained. The frequency will be the greater the
stronger the suction, and may, under certain circumstances,
reach hundreds and even thousands per second. It scarcely need
be stated that instead of one several explosion chambers may
be used for cooling purposes and also to increase the number
of active impulses and the output of the machine.

Apparatus as
illustrated in Figure 4 presents the advantage of extreme
simplicity, cheapness and reliability, there being no
compressor, buckets or troublesome valve mechanism. It also
permits, with the addition of certain well-known accessories,
the use of any king of fuel and thus meets the pressing
necessity of a self-contained, powerful, light and compact
internal combustion motor for general work. When the
attainment of the highest efficiency is the chief object, as
in machines of large size, the explosive constituents will be
supplied under high pressure and provision made of maintaining
a vacuum at the exhaust. Such arrangements are quite familiar
and lend themselves so easily to this improvement that an
enlargement on this subject is deemed unnecessary.

The
foregoing description will readily suggest to experts
modifications, both as regards construction and application of
the device and I do not wish to limit myself in these
respects. The broad underlying idea of the invention is to
permit the free passage of a fluid through a channel in the
direction of the flow and to prevent its return through
friction and mass resistance, thus enabling the performance of
valve functions without any moving parts and thereby extending
the scope and usefulness of an immense variety of mechanical
appliances.

I do not
claim the methods of and apparatus for the propulsion of
fluids and thermodynamic transformation of energy herein
disclosed, as these will be made subjects of separate
applications.

I am aware
that asymmetrical conduits have been constructed and their use
proposed in connection with engines, but these have no
similarity wither in their construction or manner of
employment with my Valvular conduit. They were incapable of
acting as valves proper, for the liquid was merely arrested in
pockets and deflected through 90 deg, this result having at best
only 25% of the efficiency attained in the construction herein
described. In the conduit I have designed the fluid, as stated
above, is deflected in each cycle through 360 deg, and a
coefficient approximating 200 can be obtained so that the
device acts a s a slightly leaking valve, and for that reason
the term "Valvular" has been given to it in contrast to
asymmetrical conduits, as heretofore proposed, which are not
Valvular in action, but merely asymmetrical as to resistance.

Furthermore,
the conduits heretofore constructed were intended to be used
in connection with slowly reciprocating machines, in which
case enormous conduit-length would be necessary, all this
rendering them devoid of practical value. By the use of an
effective Valvular conduit, as herein described, and the
employment of pulses of very high frequency, I am able to
condense my apparatus and secure such perfect action as to
dispense successfully with valves in numerous forms of
reciprocating and rotary engines.

The high
efficiency of the device, irrespective of the character of the
pulses, is due to two causes: first, rapid reversal of
direction of flow and, second, great relative velocity of the
colliding fluid columns, As will be readily seen each bucket
causes a deviation through an angle of 180 deg, and another
change of 180 degrees occurs in each of the spaces between
adjacent buckets. That is to say, from the time the fluid
enters or leaves on of the recesses to its passage into, or
exit from, the one following a complete cycle, or deflection
through 360 deg is effected. Observe now that the velocity is but
slightly reduced in the reversal so that the incoming and
deflected fluid columns meet with a relative speed, twice that
of the flow, and the energy of their impact is four times
greater than with a deflection of only 90 deg , as might be
obtained with pockets such as have been employed in
asymmetrical conduits for various purposes. The fact is,
however, that in these such deflection is not secured, the
pockets remaining filled with comparatively quiescent fluid
and the latter following a winding path of least resistance
between the obstacles interposed. In such conduits the action
cannot be characterized as Valvular because some of the fluid
can pass almost unimpeded in a direction opposite to the
normal flow. In my construction, as above indicated, the
resistance in the reverse may be 200 times that in the normal
direction. Owing to this a comparatively very small number of
buckets or elements is required for checking the fluid. To
give a concrete idea, suppose that the leak from the first
element is represented by the fraction 1/X, then after the *n*th
bucket is traversed, only a quantity (1/X)n will
escape and it is evident that X need not be a large number to
secure a nearly perfect Valvular action.

What I claim
is: -- [Claims not included here]

---

**Links**

http://www.execpc.com/~teba
(Tesla
Engine Builders Association)   
http://www.dnai.com/~zap/turbine.txt (Boundary Layer
Breakthrough by Jeffrey Hayes)   
http://www.frank.germano.com/tesla\_turbine.htm (Frank
Germano's work)   
http://www.lindsaybks.com/bks5/tturb/index.html (W. Cairns: *The
Tesla
Disc Turbine*; Lindsay Publications)   
http://www.tfcbooks.com/mall/turbomac.htm (21st Century Books
~ Tesla Turbomachinery)   
http://groups.yahoo.com/group/TheTeslaTurbineList (Yahoo
Discussion Group)   
http://www.sredmond.com/disk\_turbine.htm (S. Redmond's Tesla
Turbine)   
http://www.stanford.edu/~hydrobay/lookat/tt.html (Alan
Swithenbank's Tesla Turbine)

---

![](tturb1.jpg)


---

**[Page 2](turbine2.htm) >>> ( N. Tesla:
British Patent # 179,043 ~ "Production of High Vacua" // N.
Tesla: British Patent # 186,082 ~ "Improvements in the
Construction of Steam and Gas Turbines" //  N. Tesla:
British Patent # 186,083 ~ "Economic Transformation of the
Energy of Steam by Turbines" //  N. Tesla: British
Patent # 186,084 ~ "Improved Process & Apparatus for
Deriving Motive Power from Steam" // N. Tesla: British
Patent # 186,799 ~ "Process & Apparatus for Balancing
Rotating Machine Parts" )**

**[Page 3](turbine3.htm) >> R. Hedin: "The
Tesla Turbine" (Construction Plans); *Live Steam*
(Nov. 1984) // Warren Rice: "Tesla Turbomachinery"; Proc. IV
International Nikola Tesla Symposium (Sept. 23-25, 1991)**

---