Historical Background of the Tesla Turbine and Pump
abstract from US patent # 1,329,559,
issued to Nikola Tesla in 1916.
The Internal Combustion version of Tesla’s Turbine
Tesla’s Valvular Conduit Patent: Fig. 4 (left) 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 bucket-wheel. 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 casting 23, the central cavity 24 of which forms the combustion chamber. To prevent injury through excessive heating a jacket25 may be used, or else water injected, and when these means are objectionable recourse may be had to air cooling, this all the more readily as very high temperatures are practicable. The top of casting 23 is closed by a plate 26 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 piece 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 30 and 31. The exhaust openings 32 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 influx, 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 atmosphere 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 conditions, 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 pulses and the output of the machine.
Apparatus as illustrated in Fig. 4 presents the advantages 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 kind 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 for 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 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 degrees, and another change of 180 degrees occurs in each of the spaces between two adjacent buckets.
That is to say, from the time the fluid enters or leaves one of the recesses to its passage into, or exit from, the one following a complete cycle, or deflection through 360 degrees, 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 degrees, 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. Complete Patent information – Tesla’s Valvular Conduit Patent –
A NEW ADVANCE IN TESLA TURBINE THEORY
Observant students of the Tesla Turbine design might have wondered why some of Tesla’s engines do not appear to use a labyrinth seal between the end disks and the corresponding engine casing end plates. After all, the patent drawings clearly show these seals and the accompanying text describes them at length. At the same time, photographs of the dual 200 H.P. turbine installed at the Edison Waterside plant in New York reveal an absence of this feature.
It is believed the answer lies in the design of the engine’s inlet nozzle. (click on image – left – for larger view) It has been proposed that the slot shaped nozzle might have been constructed in such a manner that the propelling gas was never allowed to enter directly into the two interdiscular spaces nearest to the ends of the rotor.
In other words, it is believed the nozzle slot was narrower than the overall width of the rotor, by slightly more than two spaces. It might be said that the total number of disks was greater by two than the number of active disks. For example, a turbine with 25 disks, including the thicker end disks, might be described as having 23 active disks. This would allow any of the propelling gas which did get past the outermost active disks to pass through the two outermost interdiscular spaces rather than between the end disks and the engine’s end plates, specifically…Compliments: Gary Peterson (Twenty First Century Books).
Tesla’s two variations of inlet nozzles
In FIG #4, Tesla used a variable inlet nozzle #12, and controlled the amount of gas entering by a movable “block” – #13.
Note that also, in FIG #4, the inlet and exhaust port size was increased, to allow for more power, on demand.
Tesla, in FIG #5 used a diverging inlet nozzle – #15, controlled by a “butterfly” valve, #16 .
This design was to be incorporated into Tesla’s ”flying machine”, with two 10” turbines, rated at 400 HP
REF: Tesla Patent # 1,655,114 of 1928.
A word about inlet nozzles and the Anharmonic Resonator:
Looking at the diagram of the anharmonic resonator (which would include the types of nozzles Tesla was using); Sonic gas speed will occur at the smallest area cross section between a high pressure reservoir and the turbine discs. Supersonic gas flow speeds will only occur immediately downstream of a region of sonic speed (smallest cross section) and only if the cross section gradually increases. This has been proven in laboratories hundreds of times. If all gas flow properties are being regulated at the inlet nozzle immediately upstream of the turbine discs, that will be the region where sonic gas speed will occur. All cross sections upstream of the nozzle and up to the exit of the high-pressure reservoir would have a greater cross-section area. The best location to regulate gas pressure and the mass flow rate of the gas would be at the inlet nozzle, not the reservoir outlet.
The anharmonic resonator (click image thumbnail, left to enlarge) will be used downstream of a regulator valve that would also be the exit of the high pressure gas reservoir. Sonic gas speed will occur in that regulator valve (it will regulate the mass flow rate of the gas and also its pressure) and the gas flow downstream of the regulator valve would go supersonic if cross section area gradually increases. Under these conditions, a device like the aharmonic resonator could break up the supersonic shock waves ahead of a Tesla turbine intake. To slow supersonic gas, the cross section area needs to be reduced. The anharmonic resonator is essentially a modification of the Oswatitsch intake that is used at the entrance to the engines of supersonic aircraft. The Macrosonix-type intake would break up the sound waves so as to reduce the pressure loss as the air slows from supersonic speed to subsonic speed.
This device will only have use if the gas flowing toward the intake nozzle of a Tesla turbine is already traveling at supersonic speed. If the gas speed is subsonic and with no hope of it ever going supersonic, then the device would either do nothing or it will cause problems if it is not designed properly. If you want to run a Tesla turbine when the air at the intake to the nozzle is supersonic, an Oswatitsch intake may involve lower energy losses that this resonator. Both devices would work best in an aircraft traveling at supersonic speed and a Tesla turbine was being used on board to drive electrical generation equipment or hydraulic equipment.
Mass flow rate of gas into a Tesla turbine can be regulated by using a rectangular cross-section of inlet nozzle. It is very easy to achieve adjustable and variable cross-section area from a rectangular nozzle. An alternative would be to use multiple nozzles of varying cross-section areas. Operate some nozzles and keep others shut off so as to achieve the desired mass flow rate of gas into the Tesla Discs. 4-nozzles in a 1:2:4:8 cross section ratio will give a 1:2:4:8 mass flow rate ratio into the Tesla discs, which in turn would yield 15-mass flow settings and also 15-power settings in equal steps.
From the “New York Herald Tribune”, Oct. 15th 1911
Tesla’s New Monarch of Machines
Suppose some one should discover a new mechanical principle–something as fundamental as James Watt’s 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 verist 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 airplane 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 electrochemical 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 plough 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 airplane 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 center 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 center of these disks–you see the centers 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 draughts men 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 airplanes 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 center 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 Lusitanian 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 airplane practical,” I suggested.
“Not the airplane, 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 airplane feasible. There is nothing new about the airplane 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 airplane driven by your engine?” I asked. “Not at all,” said Dr. Tesla. “The airplane is fatally defective. It is merely a toy–a sporting plaything. 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 airplane 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 airplane 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 airplane. 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 airplane 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.”
The Tesla Pump
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 plough 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 airplane 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 center 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 center of these disks–you see the centers 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 draughts men 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…
NIKOLA TESLA’S DISK TURBINE
Tomorrow’s Gas Engine Is At Our Doorstep
Since its invention more than 100 years ago the reciprocating explosive gas engine has handily served mankind as we have sought to replace raw muscle power with that of the machine. In this type of motor a linear motion is given to one or more pistons by the compression and explosion of a combustible mixture of vaporized fuel and air. The energy released by the explosion is transmitted to a crank shaft which converts the reciprocating movement into rotation. With the passage of time the primitive device of the 1860s has evolved into a complex marvel of machinery capable of propelling an automobile at speeds in excess of 300 mph and yet it still bears the same basic configuration and the same mode of operation as that of its earliest ancestor.
An alternative to the reciprocating engine is the rotary engine. The most common form of these machines, the conventional bladed turbine, is used for everything from the propulsion of aircraft and large ships to stationary power generation. While working in a somewhat different manner as the machine described above, the end result of its operation is still the same – the creation of torque. Among the advantages to be gained from this design option is a reduction in the number of moving parts. In the rotary engine the piston, connecting rod, crankshaft, and flywheel are replaced by a single moving component known as a rotor. In direct contrast to the typical reciprocating engine, a well balanced rotary engine will operate virtually without vibration. Other advantages include an increase in power to weight ratio and better fuel economy. On the other side of the coin, bladed turbines are highly precision machines built to very close tolerances, and thus are much more expensive.
Nikola Tesla’s disk turbine, the Tesla Turbine , which is said to approach the ideal rotary heat engine, can be viewed as an inexpensive alternative to the bladed turbine. It consists simply of multiple shaft mounted disks suspended upon bearings which position the rotor system within a cylindrical casing. In operation high velocity gases enter tangentially at the periphery of the disks, flow between them in free spiral paths to exit, depleted of energy, through central exhaust ports. The slight viscosity of the moving gas along with its adhesion to the disks’ faces combine to drag them along, efficiently transferring the fuel’s energy to the disks and on to the shaft.
The central component of this unique engine, the rotor, is built up using eight basic components: ported disks, star washer spacers, ring washer spacers and rivets, all of which constitute the runner subassembly, and the rotor shaft with its shaft keys, bearings and lock nuts. Fabrication of the runner is fairly straight forward. The parts are assembled with the aid of a stub shaft that has three key ways machined in it to line up with three complimentary key ways machined in the center hole of each disk. The stub shaft’s length should be about three times the intended width of the runner. One end of the shaft is threaded and a shoulder ring is fastened just over a third of the way in from that end.
Assembly begins by slipping one of the thicker end disks on to the shaft. With the rivets inserted the first set of spacers are installed followed by the first thin disk. Additional spacers and disks are added in sequence with the second end disk going on last. (An operational note: In addition to providing spacing and support to the disks, each ring spacer also adds a small amount of lift that helps to propel the runner around.) At this point half a dozen or more “C” clamps are used to compress the subassembly so the rivets can be tightly peened down. The next step is truing up of the runner’s width with a surface cut across the faces of the two end disks.
While it is not as critical, the runner’s outside circumference can also be trued up at this point. Care should be exercised here to reduce the chance of damage. Any burrs and irregularities can next be removed with a narrow cutting tool. Now that the runner subassembly is nearly completed all that remains to be done is to remount it on the actual motor shaft for dynamic balancing. This is done with the aid of sophisticated machinery through the removal metal from appropriate locations around the runner’s perimeter by the drilling of shallow holes near or directly into the outer edges of the end disks.
As a starting point, the thickness of the spacers and thus the dimension of the intra-discular space can be approximated using the depth of boundary layer of air adjacent to the disks’ surfaces. The boundary layer’s true depth will depend somewhat upon the temperature and density of the propelling gas. Drawing on the science of aerodynamics we learn that the boundary layer on the skin of an aircraft in flight is approximately .020 of an inch in depth.
So, it can be assumed the layer on each side of the disks is nearly .020″ thick also. If the disk spacing were to exceed .040″ there would be a space through which some of the propelling fluid could flow and fail to effectively interact with the gas molecules making up the boundary layer. Reduce the spacing to .040″ and the two layers could be said to come in contact with each other. This sets the maximum limit of spacing. With a spacing of .030″, a standard thickness of 304 stainless sheet stock, the two layers would overlap by .010″. The practical experience of at least one disk turbine builder lends support to the use of .030″ for the thickness of the spacers and the disks as well.
The engine rotor housing or casing as described in Tesla’s turbine patent consists of two basic elements, not counting seals. These are a central ring casting and two end plate castings to which the flange pillow block bearing assemblies are bolted. As can be seen from the figure an alternative configuration involves the use of an upper and lower casting. A third option incorporates four castings, both left and right, top and bottom.
Many independent builders choose the first option, preferring to bypass the casting process and mill all of their housing components from commercially available stock. Another important element associated with the casing is the inlet nozzle through which the propelling fluid is introduced. If reversibility is desired, a second nozzle can be installed for the introduction of fluid in the opposite direction. Using compressed air or even steam to operate such a motor as described here is fairly straight forward. All that is needed is a compressor or a conventional boiler as the source of pressurized fluid. If, however, this motor is to be run on gasoline or some other explosive fuel it needs an accessory apparatus or fluid pressure generator into which the fuel and air are injected, to mix and than be ignited. The products of combustion that are developed, along with steam, if water is also injected, are then directed through a nozzle into the rotor housing.
Such pressure generating appliances that are used in conjunction with upstream compressor stages already exist. In them an ignited fuel air mixture is continuously burned to provide a nearly uniform flame front. Another important creation of Nikola Tesla’s, called the valvular conduit, simplifies the design even further by reducing the need for a compressor while also making possible the introduction of a modified combustion regime. When incorporated at the combustion chamber inlets the valvular action of this device makes the turbine more like an internal combustion engine. While introduction of fuel and air proceeds as usual, immediately upon the point of ignition all of the inlets are effectively closed. This is due to the action of the valvular conduit which, without moving parts, has the singular property of permitting free flow to occur in one direction only.
After the hot gases enter into the turbine, natural venting working in combination with an optional compressor or downstream ventilator clears the combustion chamber and promotes the introduction of another charge. In such a manner successive explosions of the fuel air mixture occur and are projected through the nozzle. The rapidity of these pulses depends primarily upon the volume of the combustion chamber and the degree of ventilation. In speaking of their frequency Tesla said, “I have been able to speed up the rate of such explosions until the sound of exploding gasses produced a musical note.”
What improvements might be made to the basic disk turbine design? Between 1906 and 1927 Tesla made real progress optimizing the engine. Nevertheless, it is reasonable to expect that some further work could have a positive effect on the machine’s performance. A first step might be to evaluate the properties of the propelling fluid as it exists while inside the engine casing. In this way the intra-discular spacing might be modified in response to the actual boundary layer depth and physical conditions at and near the disk surfaces. Another possibility lies in working with the number, size and distribution of the rivets and more importantly the ring washer spacers that are positioned between the turbine disks. A third area warranting serious investigation relates to the materials used in construction of the runner subassembly.
It is well known that any increase in the allowable turbine operating temperature results in higher engine efficiency. Turbine engineers have long sought exotic materials out of which to fabricate their turbine blades, the most heat sensitive component. These efforts have resulted in the development of a variety of suitable materials. One of the best that is presently being used is a complex super alloy known as Inconel. Its three principal constituents are: nickel (60%), chromium (16%), and cobalt (8.5%), with lesser amounts of aluminum, titanium, tungsten, molybdenum, tantalum and cadmium. Inconel has proven capable of sustaining turbine inlet temperatures of 1,832 F. It is interesting to note that some of Tesla’s turbine disks were fabricated out of a material known as German Silver. This hard alloy, once commonly used for tableware, also contains nickel along with copper and zinc in varying proportions.
No doubt the super high performance heat engines of the future will be constructed of even more advanced temperature resistant, high strength materials. There are a number of promising possibilities in this regard. One prospect is injection-molded silicon nitride (Si3N4) strengthened with silicon carbide (SiC) whiskers. Components formed out of this ceramic composite are processed using a technique known as Hot Isostatic Pressing (HIP).
Another candidate is a metal matrix composite of niobium (Nb) combined with tungsten mesh, or refractory fibers of Nicalon or FP-Al2O3 for reinforcement. Components made of niobium matrix composites require an iridium coating for oxidation protection. A third promising contestant that has been identified is a reaction milled composite called AlN dispersoid-reinforced NiAl. This nickel-aluminum alloy based material is produced by milling NiAl powder in liquid nitrogen. While actual performance data are not yet available for the NiAl/AlN composite, tests show that it compares very favorably with other super alloys that are presently being used.
A related material known as single crystal NiAl has already been formed into turbine blades and could be adopted immediately. A near term benefit to be derived from the use of this material, as with the other NiAl compounds, would be a substantial reduction in weight. In this case weight savings in a conventional rotor blade and disk system would be about 40%. Furthermore, it is expected that techniques will be developed to control high temperature deformation of these oxidation resistant materials. This will result in heat engines with further reduced cooling requirements and even higher operating temperatures.
Dr. Tesla’s engineering legacy when placed in context with recent developments in the areas of conventional turbine engine design, tooling, materials processing and electronics establishes a secure platform for the development of a radically new type of automobile engine and drive train. By adopting an interdisciplinary approach that incorporates new light weight carbon fiber composite materials, advanced power electronics and microprocessors in combination with hydraulics and our best electric motors we can have a form of personal transportation such as the world has never seen. The vehicles of the twenty-first century promise to be more efficient, economical, durable, better performing and easy on the environment than anything we have on the road today!
compliments: Gary Peterson – 21st Century Books, http://www.tfcbooks.com used by permission.
WHEN his World Wireless System project crashed, Tesla turned again to a project to which he had given considerable thought at the time he was developing his poly phase alternating-current system: that of developing a rotary engine which would be as far in advance of existing steam engines as his alternating-current system was ahead of the direct-current system, and which could be used for driving his dynamos. All of the steam engines in use in powerhouses at that time were of the reciprocating type; essentially the same as those developed by Newcomer and Watt, but larger in size, better in construction and more efficient in operation. Tesla’s engine was of a different type–a turbine in which jets of steam injected between a series of disks produced rotary motion at high velocity in the cylinder on which these disks were mounted. The steam entered at the outer edge of the disks, pursued a spiral path of a dozen or more convolutions, and left the engine near the central shaft.
When Tesla informed a friend in 1902 that he was working on an engine project, he declared he would produce an engine so small, simple and powerful that it would be a ”powerhouse in a hat.” The first model, which he made about 1906, fulfilled this promise. It was small enough to fit into the dome of a derby hat, measured a little more than six inches in its largest dimension, and developed thirty horsepower. The power-producing performance of this little engine vastly exceeded that of every known kind of prime mover in use at that time.
The engine weighed a little less than ten pounds. Its output was therefore three horsepower per pound. The rotor weighed only a pound and a half, and its light weight and high power yield gave Tesla a slogan which he used on his letterheads and envelopes–”Twenty horsepower per pound.” There was nothing new, of course, in the basic idea of obtaining circular motion directly from a stream of moving fluid. Windmills and water wheels, devices as old as history, performed this feat. Hero, the Alexandrian writer, about 200 bc, described, but he did not invent, the first turbine. It consisted of a hollow sphere of metal mounted on an axle, with two tubes sticking out of the sphere at a tangent to its surface. When water was placed in the sphere and the device was suspended in a fire, the reaction of the steam coming out of the tubes caused the device to rotate.
Tesla’s ingenious and original development of the turbine idea probably had its origin in that amusing and unsuccessful experiment he made when, as a boy, he tried to build a vacuum motor and observed its wooden cylinder turn slightly by the drag of the air leaking into the vacuum chamber. Later, too, when as a youth he fled to the mountains to escape military service and played with the idea of transporting mail across the ocean through an underwater tube, through which a hollow sphere was to be carried by a rapidly moving stream of water, he had discovered that the friction of the water on the walls of the tube made the idea impracticable. The friction would slow down the velocity of the stream of water so that excessive amounts of power would be required to move the water at a desired speed and pressure. Conversely, if the water moved at this speed, the friction caused it to try to drag the enclosing tube along with it.
It was this friction which Tesla now utilized in his turbine. A jet of steam rushing at high velocity between disks with a very small distance separating them was slowed down by the friction–but the disks, being capable of rotation, moved with increasing velocity until it was almost equal to that of the steam. In addition to the friction factor, there exists a peculiar attraction between gases and metal surfaces; and this made it possible for the moving steam to grip the metal of the disks more effectively and drag them around at high velocities. The first model which Tesla made in 1906 had twelve disks five inches in diameter. It was operated by compressed air, instead of steam, and attained a speed of 20,000 revolutions per minute. It was Tesla’s intention eventually to use oil as fuel, burning it in a nozzle and taking advantage of the tremendous increase in volume, in the change from a liquid to burned highly expanded gases, to turn the rotor. This would eliminate the use of boilers for generating steam and give the direct process proportional increased efficiency.
Had Tesla proceeded with the development of his turbine in 1889 when he returned from the Westinghouse plant, his turbine might perhaps have been the one eventually developed to replace the slow, big, lumbering reciprocating engines then in use. The fifteen years, however, which he devoted to the development of currents of high potential and high frequency, had entailed a delay which gave opportunity for developers of other turbine ideas to advance their work to a stage which now was effective in putting Tesla in the status of a very late starter. In the meantime, turbines had been developed which were virtually windmills in a box. They consisted of rotors with small buckets or vanes around the circumference which were struck by the incoming steam jet. They lacked the simplicity of the Tesla turbine; but by the time Tesla introduced his type, the others were well entrenched in the development stage. Tesla’s first tiny motor was built in 1906 by Julius C. Czito, who operated at Astoria, Long Island, a machine shop for making inventor’s models. He also built the subsequent 1911 and 1925 models of the turbine, and many other devices on which Tesla worked up to 1929. Mr. Czito’s father had been a member of Tesla’s staff in the Houston Street laboratories, from 1892 to 1899, and at Colorado Springs.
Mr. Czito’s description of the first model is as follows: “The rotor consisted of a stack of very thin disks six inches in diameter, made of German silver. The disks were one thirty-second of an inch thick and were separated by spacers of the same metal and same thickness but of much smaller diameter which were cut in the form of a cross with a circular center section. The extended arms served as ribs to brace the disks…There were eight disks and the edgewise face of the stack was only one-half inch across. They were mounted on the center of a shaft about six inches long. The shaft was nearly an inch in diameter in the mid section and was tapered in steps to less than half an inch at the ends. The rotor was set in a casing made in four parts bolted together.
The circular chamber where the rotor turned was accurately machined to allow a clearance of one sixty-fourth of an inch between the casing and the face of the rotor. Mr. Tesla desired an almost touching fit between the rotor face and the casing when the latter was turning. The large clearance was necessary because the rotor attained tremendously high speeds, averaging 35,000 revolutions per minute. At this speed the centrifugal force generated by the turning movement was so great it appreciably stretched the metal in the rotating disks. Their diameter when turning at top speed was one thirty-second of an inch greater than when they were standing still.” A larger model was built by Tesla in 1910. It had disks twelve inches in diameter, and with a speed of 10,000 revolutions per minute it developed 100 horsepower, indicating a greatly improved efficiency over the first model. It developed more than three times as much power at half the speed. During the following year, 1911, still further improvements were made. The disks were reduced to a diameter of 9.75 inches and the speed of operation was cut down by ten per cent, to 9,000 revolutions per minute–and the power output increased by ten per cent, to 110 horsepower!
Following this test, Tesla issued a statement in which he declared: I have developed 110 horsepower with disks nine and three quarter inches in diameter and making a thickness of about two inches. Under proper conditions the performance might have been as much as 1,000 horsepower. In fact there is almost no limit to the mechanical performance of such a machine. This engine will work with gas, as in the usual type of explosion engine used in automobiles and airplanes, even better than it did with steam. Tests which I have conducted have shown that the rotary effort with gas is greater than with steam. Enthusiastic over the success of his smaller models of the turbine, operated on compressed air, and to a more limited extent by direct combustion of gasoline, Tesla designed and built a larger, double unit, which he planned to test with steam in the Waterside Station, the main powerhouse of the New York Edison Company.
This was a station which had originally been designed to operate on the direct-current system developed by Edison–but it was now operating throughout on Tesla’s poly phase alternating-current system. Now Tesla, invading the Edison sanctum to test a new type of turbine which he hoped would replace the types in use, was definitely in enemy territory. The fact that he had Morgan backing, and that the Edison Company was a “Morgan company,” had no nullifying effect on the Edison-Tesla feud. This situation was not softened in any way by Tesla’s method of carrying on his tests. Tesla was a confirmed ”sun dodger”; he preferred to work at night rather than in the daytime.
Powerhouses, not from choice but from necessity, have their heaviest demands for current after sunset. The day load would be relatively light; but as darkness approached, the dynamos started to groan under the increasing night load. The services of the workers at the Waterside Station were made available to Tesla for the setting up and tests of his turbine with the expectation that the work would be done during the day when the tasks of the workers were easiest. Tesla, however, would rarely show up until five o’clock in the afternoon, or later, and would turn a deaf ear to the pleas of workers that he arrive earlier. He insisted that certain of the workers whom he favored remain after their five-o’clock quitting time on the day shift to work with him on an overtime basis. Nor did he maintain a conciliatory attitude toward the engineering staff or the officials of the company. The attitudes, naturally, were mutual.
The turbine Nikola Tesla built for this test had a rotor 18 inches in diameter which turned at a speed of 9,000 revolutions per minute. It developed 200 horsepower. The overall dimensions of the engine were–three feet long, two feet wide and two feet high. It weighed 400 pounds. Two such turbines were built and installed in a line on a single base. The shafts of both were connected to a torque rod. Steam was fed to both engines so that, if they were free to rotate, they would turn in opposite directions. The power developed was measured by the torque rod connected to the two opposing shafts. At a formal test, to which Tesla invited a great many guests, he issued a statement in which he said, as reported, in part:
“It should be noted that although the experimental plant develops 200 horsepower with 125 pounds at the supply pipe and free exhaust it could show an output of 300 horsepower with full pressure of the supply circuit. If the turbine 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 28.5 to 29.0 inches of vacuum the results obtained in the present high pressure machine indicate that the compounded unit would give an output of 600 horsepower without great increase of dimensions. This estimate is very conservative.”
Tests have shown that when the turbine is running at 9,000 revolutions per minute under an inlet pressure of 125 pounds to the square inch and with free exhaust 200 brake horsepower are developed. The consumption under these conditions of maximum output is 38 pounds of saturated steam per horsepower per hour, a very high efficiency when we consider that the heat drop, measured by thermometers, is only 130 B.T.U. and that the energy transformation is effected in one stage. Since three times the number of heat units are available in a modern plant with superheat and high vacuum the utilization of these facilities would mean a consumption of less than 12 pounds per horsepower hour in such turbines adapted to take the full drop.
Under certain conditions very high thermal efficiencies have been obtained which demonstrate that in large machines based on this principle steam consumption will be much lower and should approximate the theoretical minimum thus resulting in the nearly frictionless turbine transmitting almost the entire expansive energy of the steam to the shaft. It should be kept in mind that all of the turbines which Tesla built and tested were single-stage engines, using about one-third of the energy of the steam. In practical use, they were intended to be installed with a second stage which would employ the remaining energy and increase the power output about two or three fold. (The two types of turbines in common use each have a dozen and more stages within a single shell.)
Some of the Edison electric camp, observing the torque-rod tests and apparently not understanding that in such a test the two rotors remain stationary–their opposed pressures staging a tug of war measured as torque–circulated the story that the turbine was a complete failure; that this turbine would not be practical if its efficiency had been increased a thousand fold. It was stories such as these that contributed to the imputation that Tesla was an impractical visionary. The Tesla turbine, however, used as a single-stage engine, functioning as a pygmy power producer, in the form in which it was actually tested, anticipated by more than twenty five years a type of turbine which has been installed in recent years in the Waterside Station. This is a very small engine, with blades on its rotor, known as a ”topping turbine,” which is inserted in the steam line between the boilers and the ordinary turbines. Steam of increased pressure is supplied, and the topping turbine skims this “cream” from the steam and exhausts steam that runs the other turbines in their normal way. The General Electric Company was developing the Curtis turbine at that time, and the Westinghouse Electric and Manufacturing Company was developing the Parsons turbine; and neither company showed the slightest interest in Tesla’s demonstration.
Further development of his turbine on a larger scale would have required a large amount of money–and Tesla did not possess even a small amount. Finally he succeeded in interesting the Allis Chalmers Manufacturing Company of Milwaukee, builders of reciprocating engines and turbines, and other heavy machinery. In typical Tesla fashion, though, he manifested in his negotiations such a lack of diplomacy and insight into human nature that he would have been better of if he had completely failed to make any arrangements for exploiting the turbine.
Tesla, an engineer, ignored the engineers on the Allis Chalmers staff and went directly to the president. While an engineering report was being prepared on his proposal, he went to the Board of Directors and ”sold” that body on his project before the engineers had a chance to be heard. Three turbines were built. Two of them had twenty disks eighteen inches in diameter and were tested with steam at eighty pounds pressure. They developed at speeds of 12,000 and 10,000 revolutions per minute, respectively, 200 horsepower. This was exactly the same power output as had been achieved by Tesla’s 1911 model, which had disks of half this diameter and was operated at 9,000 revolutions under 125 pounds pressure. A much larger engine was tackled next. It had fifteen disks sixty inches in diameter, was designed to operate at 3,600 revolutions per minute, and was rated at 500 kilowatts capacity, or about 675 horsepower. Hans Dahlstrand, Consulting Engineer of the Steam Turbine Department, reports, in part:
We also built a 500 kw steam turbine to operate at 3,600 revolutions. The turbine rotor consisted of fifteen disks 60 inches in diameter and one eighth inch thick. The disks were placed approximately one eighth inch apart. The unit was tested by connecting to a generator. The maximum mechanical efficiency obtained on this unit was approximately 38 per cent when operating at steam pressure of approximately 80 pounds absolute and a back pressure of approximately 3 pounds absolute and 100 degrees F superheat at the inlet. When the steam pressure was increased above that given the mechanical efficiency dropped, consequently the design of these turbines was of such a nature that in order to obtain maximum efficiency at high pressure, it would have been necessary to have more than one turbine in series.
The efficiency of the small turbine units compares with the efficiency obtainable on small impulse turbines running at speeds where they can be directly connected to pumps and other machinery. It is obvious, therefore, that the small unit in order to obtain the same efficiency had to operate at from 10,000 to 12,000 revolutions and it would have been necessary to provide reduction gears between the steam turbine and the driven unit. Furthermore, the design of the Tesla turbine could not compete as far as manufacturing costs with the smaller type of impulse units. It is also questionable whether the rotor disks, because of light construction and high stress, would have lasted any length of time if operating continuously. The above remarks apply equally to the large turbine running at 3,600 revolutions. It was found when this unit was dismantled that the disks had distorted to a great extent and the opinion was that these disks would ultimately have failed if the unit had been operated for any length of time.
The gas turbine was never constructed for the reason that the company was unable to obtain sufficient engineering information from Mr. Tesla indicating even an approximate design that he had in mind. Tesla appears to have walked out on the tests at this stage. In Milwaukee, however, there was no George Westinghouse to save the situation. Later, during the twenties, the author asked Tesla why he had terminated his work with the Allis Chalmers Company. He replied: ”They would not build the turbines as I wished”; and he would not amplify the statement further. The Allis Chalmers Company later became the pioneer manufacturers of another type of gas turbine that has been in successful operation for years.
While the Dahlstrand report may appear to be severely critical of the Tesla turbine and to reveal fundamental weaknesses in it not found in other turbines, such is not the case. The report is, in general, a fair presentation of the results; and the description of apparent weaknesses merely offers from another viewpoint the facts which Tesla himself stated about the turbine in his earlier test–that when employed as a single-stage engine it uses only about a third of the energy of the steam, and that to utilize the remainder, it would have to be compounded with a second turbine. The reference to a centrifugal force of 70,000 pounds resulting from the high speed of rotation of the rotor, causing damage to the disks, refers to a common experience with all types of turbines. This is made clear in a booklet on ”The Story of the Turbine,” issued during the past year by the General Electric Company, in which it is stated: It [the turbine] had to wait until engineers and scientists could develop materials to withstand these pressures and speeds. For example, a single bucket in a modern turbine traveling at 600 miles per hour has a centrifugal force of 90,000 pounds trying to pull it from its attachment on the bucket wheel and shaft. . . .
In this raging inferno the high pressure buckets at one end of the turbine run red hot while a few feet away the large buckets in the last stages run at 600 miles per hour through a storm of tepid rain–so fast that the drops of condensed steam cut like a sand blast. Dahlstrand reported that difficulties were encountered in the Tesla turbine from vibration, making it necessary to re-enforce the disks. That this difficulty is common to all turbines is further indicated by the General Electric booklet, which states:
Vibration cracked buckets and wheels and wrecked turbines, sometimes within a few hours and sometimes after years of operation. This vibration was caused by taking such terrific amounts of power from relatively light machinery–it some cases as much as 400 horsepower out of a bucket weighing but a pound or two. . . .
The major problems of the turbine are four–high temperatures, high pressures, high speeds and internal vibration. And their solution lies in engineering, research and manufacturing skill. These problems are still awaiting their final solution, even with the manufacturers who have been building turbines for forty years; and the fact that they were encountered in the Tesla turbine, and so reported, is not a final criticism of Tesla’s invention in the earliest stages of its development.
The development of new alloys, which can now almost be made to order with desired qualities of mechanical stability under conditions of high temperature and great stresses, is largely responsible for this turn of events. It is a possibility that if the Tesla turbine were constructed with the benefit of two or more stages, thus giving it the full operating range of either the Curtis or the Parsons turbine, and were built with the same benefits of engineering skill and modern metallurgical developments as have been lavished on these two turbines, the vastly greater simplicity of the Tesla turbine would enable it to manifest greater efficiencies of operation and economies of construction.
THE TESLA BLADELESS DISK TURBINE
Most people remember Nikola Tesla for his work and revelations in the field of electrical energy and the invention of radio. However, Tesla had a life long interest in developing a flying machine. Tesla had envisioned himself as the first man that would fly. He had planned to build an aircraft that would operate on electric motors. However, the first men who successfully flew an aircraft used the reciprocating internal combustion engine. Though successful in achieving flight, aircraft using these engines were dangerous and unpredictable, due to the engine’s lack of adequate power. Tesla turned his attention to revamping the internal combustion engine so as to make flying safe for all and minimize its environmental impact. Documented in this text is the result of Tesla’s endeavors and the resulting marvel of machines called the Bladeless Boundary- Layer Turbine.
Although Tesla’s dream for his engines application in aircraft was not realized in his life time, if allowed to be used in aircraft today, it would provide a quiet, safe, simple and efficient alternative to our supposedly advanced bladed turbine aircraft engines. It has been estimated that an increase in fuel efficiency of a factor of three could be realized in aircraft and thus substantially reduce pollution. Not only this, the Bladeless Tesla Turbine Engine can turn at much higher speeds with total safety. If a conventional bladed turbine engine goes critical or fails, watch out, you have exploding parts slicing through hydraulic lines, control surfaces and maybe even you. With the Bladeless Tesla Turbine this is not a danger because it will not explode. If it does go critical, as has been documented in tests at 85,000 rpm, the failed component will not explode but implode into tiny pieces which are ejected through the exhaust while the undamaged components continue to provide thrust to keep you airborne. We. can only speculate on the human suffering that could and should be averted.
The application of this amazing engine was not to be limited to aircraft. Tesla was setting up plans to replace what he considered the wasteful, polluting, inefficient and complicated reciprocating engine in all its applications, including the automobile. Tesla’s small but powerful engine has only one moving part and is 95% efficient, which means tremendous mileage. It runs vibration free and doesn’t even require a muffler. Not only is this engine 95% efficient, as compared to 25% efficiency or less of the conventional gas engine, it can run efficiently on any fuel from sawdust to hydrogen with no wear on the internal engine components. This engine’s speed-torque characteristic allows full torque at the bottom of the speed range eliminating the conventional shifting gear transmission. This provides additional economy as the expensive, complicated and wear prone transmission is eliminated.
Unlike most people of the time, Tesla was very concerned about the long range environmental damage the reciprocating engines would create. He stressed over and over how we must take the long range view and not step out of harmony with our life support systems. Today the widening concern for Spaceship Earth and the renewal of an old ethic “We don’t inherit the Earth from our ancestors, we borrow it from our children” is slowly beginning to awaken people to the concerns of Tesla.
Although the existence of the automobile on city streets dates back to the first years of the century, its role as a contributor to air contamination did not receive wide acceptance among scientists until the 60’s. Factual evidence that urban area smog was chemically related to automobile emissions had been produced and acknowledged by scientific groups in the 1950’s. Despite vehement disagreement which ensued between government and the automotive industry on this volatile issue, research and development programs were initiated by both groups in an effort to identify the reciprocating internal combustion engine’s sources of pollution and determine what corrective action might be taken. Obviously Tesla’s ounce of prevention was not heeded, leaving us with well over the pound required for a cure with nearly half of all air pollution caused by the reciprocating internal combustion engine.
The Boundary Layer Turbine is not only an engine that is hard to comprehend by our currently imposed standards, but can also be used as a pump with slight modification. And like its cousin the engine, it has Herculean power. Unlike conventional pumps that are easily damaged by contaminants, the Bladeless Tesla Pump can handle particles and corrosives in stride as well as gases with no cavitation effect that destroys, in short order, conventional type pumps.
These pumps and engines, though unknown to most, are available for commercial sale. If large scale commercial production was implemented, these engines and pumps would be extremely affordable due to their simplicity of manufacture, longevity, almost total lack of maintenance and the added bonus that they require no crank case oil.
Almost a quarter of the air pollution today comes from the coal being burned to generate electricity. Fuel consumption, resulting in air pollution and acid rain, could be significantly reduced simply by replacing the conventional blade steam turbines currently used by utilities with the Bladeless Tesla Steam Turbine. This also would have the added bonus of drastically reducing maintenance. But the real solution lies in using low temperature wet steam occurring naturally from the ground in the form of geothermal energy. This energy would destroy a conventional bladed steam turbine, unless expensive steam drying is employed. However, the Bladeless Tesla Steam Turbine requires no drying and can be connected directly to the geothermal source. It has been estimated that the geothermal potential in just Southern California alone, could power the entire North American Continent with NO POLLUTION! Large oil companies have comprehended the potential of geothermal energy and have purchased many of these large tracks of prime geothermal land.
Due to the revolutionary concepts embodied in this engine, we can easily end the so called energy crisis and dramatically reduce pollution. Even the vested energy interests are beginning to understand that now is the time for change, realizing their future health and wealth is directly linked to that of the environment. You can’t hide or buy your way out of a devastated planet. There must also be a move forward for the many misinformed environmentalists who see our future as one of regression from technology instead of its proper usage.
Tesla from his 1919 autobiography, My Inventions: “My alternating system of power transmission came at a psychological moment, as a long-sought answer to pressing industrial questions, and although considerable resistance had to be overcome and opposing interests reconciled, as usual, the commercial introduction could not be long delayed. Now, compare this situation with that confronting my turbine, for example. One should think that so simple and beautiful an invention, possessing many features of an ideal motor, should be adopted at once and, undoubtedly, it would under similar conditions. But the prospective effect of the rotating field was not to render worthless existing machinery; on the contrary, it was to give it additional value. The system lent itself to new enterprise as well as to improvement of the old. My turbine is an advance of a character entirely different. It is a radical departure in the sense that its success would mean the abandonment of the antiquated types of prime movers on which billions of dollars have been spent. Under such circumstances the progress must needs be slow and perhaps the greatest impediment is encountered in the prejudicial opinions created in the minds of experts by organized opposition.”
H.G. Wells once said that future history will be a race between education and catastrophe. This book is dedicated to the race for education. Reprinted from: Boundary-Layer Breakthrough – The Tesla Bladeless Turbine pages 114-118.
Scientific American September 30, 1911, page 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, cross head 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 practical 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 September 30, 1911, page 296
The Rotary 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 B.T.U., 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 bottom of 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 B.T.U., 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.
BOUNDARY-LAYER BREAKTHROUGH  – THE TESLA BLADELESS TURBINE
Journey back to the future and discover the fascinating secret behind the most powerful and economic internal or external combustion engine of all time: Tesla’s Bladeless Boundary-Layer Turbine. You will experience the excitement of understanding as Tesla’s mechanical breakthrough is explored, shattering the boundaries of our current mechanical standard. You will be swept into the awareness of discovery as the simplicity of this whirl wind machine of natural harmony is revealed. Unveiled here today how it is possible to convert the normally undesired energy of drag into the tremendous vortex energy of Tesla’s perfectly controlled mechanical tornado. The real answer to energy.
The history of Tesla’s monarch of machines is then followed into the present day work of researchers and inventors C.R. “Jake” Possell . and Frank Germano (President of International Turbine And Power, LLC). You will learn how modern day applications of the bladeless turbine could improve all aspects of our mechanical life. Today’s applications range from indestructible pumps and Freon free air conditioning to speed boats and supersonic aircraft.
Conventional pumps and engines pale in comparison. This jewel of mechanics has no equal. It stands alone above all others. No other pump or engine can match the longevity, economy, size, safety, silence and vibration free Herculean power of this truly elegant machine. It waits patiently to solve the efficiency and pollution problems of today and could literally usher in A NEW WORLD. Fully Illustrated
 Mr. C. R. “Jake” Possell Is President of a Public Company – QUADRATECH, Inc., 1417 South Gage Street, San Bernardino, CA 92408
 Mr. Frank Germano is President of a Private Company – International Turbine And Power, LLC, 931 Rumsey Avenue, Cody, Wyoming 82414, and Founder and CEO of Global Energy Technologies, Inc., 11th Street, Blakely, PA 18447.
 BOUNDARY-LAYER BREAKTHROUGH – THE BLADELESS TESLA TURBINE Volume II. The Tesla Technology Series, ISBN 1-882137-01-9