Hello Mark:

For what it's worth, the large diameter blades of the circular saws in an old time sawmill were hammered in the central areas producing a disc which would act like the bottom of an oil can when not spinning. Otherwise it was thought that it would not cut in a straight line when operating at speeds well under what would disintegrate the disk. You might wish to consider this principle on the disks in a Tesla turbine so that when under the influence of centrifugal force stretching the circumference to a greater degree than the interior regions waves are not formed in the disks.

I am of the opinion that while Tesla's design worked well on large volumes of steam, the blades needed to be very close and warpage caused problems, especially if high temperature gasses were involved.

ayyon

century later we have much more advanced technology in materials available :-))

I would suggest to OP to stick closely to Tesla's specifications, just use improved materials for plates, like for instance are used in computer Hard Discs, specially since some of them rotate 10 000 RPM, and those problems are surely known to them as well.

Many have tought they could improve on Tesla's design so they started experimenting and failed in consequence. Therefore make turbine first exactly as Eng. Tesla has projected it, and when You are satisfied that it work as he claimed, then You can try new ideas and experiment with them. That way You would have allways working model to fall back to, in case experimental model prove to be less efficient.........

If You intend to use such turbines for wind power generation, I would be interested in possible cooperation in that area!

Here is the question: At a given diameter and RPM, is the stress on the disc dependent on its mass? If so, then the thinner and lighter the disc, the less likely to fail catastrophically due to speed.

Also on this topic: For a thin, flexible disc, at high RPM will centripetal acceleration tend to "stiffen" the disc, making it effectively more dimensionally stable?

From what I understand from other examples of discs running at high speed (such as compact discs) the thinner discs wobble and distort at very high speeds until they fly apart (as seen on high speed camera). Trying to use flexible discs is asking for trouble especially when such close distances are needed to be maintained between discs. Balanced rigid discs are the way to go. Below is an example video of what hapens to a flexible disc traveling too fast.

http://www.buzzhumor.com/videos/2936/Mythbusters_CDROM_Shattering

If I can match Tesla's stated efficencies and power density (95% {turbine only} and 1/2 pound per horsepower) I can replace expensive, heavy, complex electric motors with cheap, light, simple turbine units.

If his original claims regarding this particular development were not a scam. From what I have seen so far no one has been able to replicate Tesla's claims.

http://en.wikipedia.org/wiki/Tesla_turbine

I would be interested in what turbine engineers think, as the claims sound fishy and turbine technology and theory is well known and proven. Special application turbine perhaps?

Tesla's later designs used a series of spacers around the perimiter of the disc, and at a sub-diameter, which maintained spacing and increased strength. It also helped starting torque, as the spacers made it a hybrid between an impulse turbine and a boundary layer turbine. Also my design calls for heavier discs at each end of the stack.

Also, I have noticed that nearly everybody playing around with these is running them with no load or governor. I intend to fashion an old fashioned brake with a 12" long arm between the output shaft and a kitchen scale (or bathroom scale, if I build a full size model.) http://en.wikipedia.org/wiki/De_Prony_brake This should allow me to tweak the critter until I get the maximum output from a fixed input (say X psi of compressed air at Y CFM.) I think I can rig a timing light to output RPM for me.

The tricky parts of Tesla's design seem to be matching the volume of fluid supplied to the turbine capacity (these little critters are very power dense) and the velocity of the incoming fluid to the working RPM. Based on my research the velocity of the incoming fluid should be about double the angular velocity of the rotor. Then the disc spacing needs to be optimized to the fluid to maintain laminar flow in the boundary layer. Ideally the working fluid spirals all the way down from the perimiter of the discs to the exhaust at the center, giving up heat and momentum until it is at just above the condensation point and just above the angular velocity of the rotor.

Also going to see how a de Laval nozzle affects the efficiency. If I put a lower volume of steam into the turbine at a higher velocity, that should reduce steam consumption.

Hi Mike,

I think disk rigidity is a rather important factor. As any fluid / gas is accelerated within a confined space/ area / boundary layer, there will be an associated decrease in pressure. I think that if the disks warped due to this pressure variance there would be quite a decrease in efficiency. Light and stiff are both required design goals. Good luck on your project - sounds interesting!

Cheers

Rogerzz

"I think disk rigidity is a rather important factor. As any fluid / gas is accelerated within a confined space/ area / boundary layer, there will be an associated decrease in pressure. I think that if the disks warped due to this pressure variance there would be quite a decrease in efficiency."

If I design it right, the pressure on each side of a disc at any given point will be equal, so that should help. For high temperature fluids, the temperature gradient from the perimiter of the discs to the center is a problem, though.

I'm making some modifications to the exhaust system for this critter that I haven't heard of being done before. If it works, that should solve a few problems.

Hey Mark,

the problem is turbulence. You inject gas or fluid between the plates where the pressure and velocity are not constant. Much like the delta vees behind a high speed jet or rocket only not so pronounced. When a high pressure shock wave passes beside a low pressure between waves the disk between is subjected to force.

The issue with Tesla's turbine efficiency is design. It peaks at one sweet spot if properly designed for that sweet spot. The disks are very close and thin to be efficient.

Brad

Don't think I will be dealing with shock waves using steam as a working fluid. The trick seems to be maintaining laminar flow through the whole rotor.

I plan to use this as a direct-drive turbine (possibly with some sort of fluid coupling), so I need efficiency across a fairly wide RPM range. I may need to play around with a variable nozzle. This will allow high flow rates at low velocity for startup, and high velocities at lower flow rates for efficiency at speed.

I'm trying to design a steam turbine unit that will match the power density and torque of a traction motor on a diesel-electric locomotive. Actually, the finished units will be used to replace the four or six traction motors on a locomotive. The diesel prime mover and main generator will be replaced by a high-efficiency biomass fueled boiler system.

Any compressible fluid changing velocity creates shock waves as it slows. The more rapid the change the larger the shock waves. The algorithm is very similar to traffic flow patterns. Think of a bunch of bed springs flowing through a pipe with a venturi in it. Temperature, velocity and pressure all get back in balance with local conditions.

The nozzles will shed vortices. If your make expansion nozzles to limit this the speed is smoothed into volume and the shock waves are much more orderly.

Are you going to try regenerative braking with this? The turbines can become pumps but it will also have to be part of the design.

Been a long day, I'm off to bed. Please keep me informed.

Brad

Good Answer there- thanks.

The nozzle design is definitely going to be key. Gustaf de Laval invented the convergent-divergent nozzle for his turbine back in 1897.

How does this sound: Focus the shock wave from a de Laval nozzle on the spacers at the edge of the rotor. When there is a large difference between the velocity of the fluid and the angular velocity of the rotor (starting and low speed) this would cause high pressure in front of the spacers and low pressure vortices behind them. This should cause a lot of force on the spacers, which is the idea. At higher rotor speeds, the flow around the spacers might be closer to laminar.

I haven't figured out a way to use this particular unit as a steam compressor for regenerative braking. I had thought of allowing condensate to flow into the turbine case, where it would create drag. Hmm. . . condensate in, friction turns it to steam, and a relief valve returns it to the boiler. This has possibilities. That would generate enough steam to run the auxiliaries (generator, air compressor, A/C) and the boiler controls could turn the feed rate down to the absolute minimum- just enough to superheat the steam from the brakes. That would really pay off for a passenger locomotive, which will need a very large auxiliary generator to handle the "head end power" requirements.

May I make a suggestion on your nozzles. Use an aero spike version of the de Laval design. The internal pressure of the turbine becomes one half of the nozzle giving a much wider range of pressure efficiencies.

A de Laval nozzle is very efficient at one set of parameters. Change one and the efficiency drops. The Aero spike minimizes this.

Brad

Hey! Now that's an idea. How does this look?

Sorry for the crudeness of the drawing. It represents a linear aerospike with a secondary jet. This will be coming out the side of a "C" shaped tube the width of the rotor. The tube will rotate through 100° or so to allow the turbine to run in either direction. I'll feed steam into both ends of the tube to maximize flow.

Needs some more thought, more sketches, and some serious number crunching (will delegate that to our PE).

Hi Mark, Split your aero spike vertically and discard the far half. Now rotate it approx. 15 °clock wise. Now the internal pressure of the turbine acts as the other half of the de Laval nozzle. If you wish to rotate the nozzle to reverse it, set your plumbing, so it feeds the appropriate side of the aero spike depending on rotation. Due to complexity it will probably be easier to just use opposing aero spike halves and valve between them. As for crudeness it conveyed the concept. While it could be flashier, unless more information is conveyed it is just bells and whistles. Brad My IE8 sems to be missing the formatting bar, more than a single space or the return and spell check in the CR4 editor?

"Split your aero spike vertically and discard the far half. Now rotate it approx. 15 °clock wise. Now the internal pressure of the turbine acts as the other half of the de Laval nozzle. "

Thanks, UV! At zero RPM, I want the flow from the nozzle to spread out, at lower velocity but using as much of the surface area of the disc as possible to generate torque. As RPMs come up, that should force the fluid to the outer edge of the disc, increasing pressure. That should bring the velocity of the fluid up in proportion to the RPM.

UV, if you'd like to get more involved in this project, email me through the forum.

Honored coleagues,

If I were you, I would first try to reproduce Tesla results from his original engineering plans. What is used here is >>Adhesive force<< between fluid and plates, and so greater is surface, better thing work. Therefore need for thin plates. Now, perhaps your nozzles would help, but then maybe they would not. Simple sharp corner between plates edge and side plate should be enough (that is just an opinion, dont shoot me!) just like in the drawing somebody has supplied, provided that backside is made so that pressure cannot go that way also. Simple pipe with slot that would let fluid out paralel to sideplate would be enough. Fluid must hit very circumference of plates tangentially, and it would then spiral toward center of plates, as OP correctly remarked. No other additions are necesary because when adhesive force grab fluid and stick it to plates, then this same fluid is pushed by more fluid and this is how kinetic energy is transfered. In process this happen not just once but many times (that is why such turbine is so effective) while fluid spiral over plates and slow down because it has lost energy, but since lenght of circumference of circle depend on its radius, so fluid comming closer to center of plates have to travel ever shorter distance, and it would regain some of kinetic energy from faster fluid that is freshly supplied, so it would again be able to transfer half of remaining energy to plates that are also moving slower at this radius. Now, my conclusion is that larger diameter of plates is, more times would fluid spiral around plates and more energy would be extracted. Speed of fluid should be double of speed at which plate edges are traveling at desired RPM that we want to achieve, just like it is with Pelton turbines, but here more kinetic energy is extracted, not just half....... I would say that for each 360 degrees that fluid spiral over plates, half of its kinetic energy is transfered. For one 360 degree path we get 50% out of originall 100%, for next 25%, for third 12.5%, then 6.25% and for fifth 3.125%, so with 5 spirals nearly 97% of energy would be extracted, if I am not wrong and interaction of fluid spirals is not transfering additional energy from one spiral to another. Only problem is to find optimum size of plates depending on fluid used (because adhesive force is different for different fluids) and plate thickness, so they would not buckle or warp from temperature transfered, which was only problem that Tesla faced 100 years ago :-)) But, this was in regard to his motor that burned fuels inside, so naturally temperature was high, and due to efficient energy transfer, this heat was transfered to plates also. Now, plate thickness in Tesla turbine is quite relatively thin, because on watermill powered by Tesla turbine in Smiljan, his birth place, there are plates one to two centimeters thick or maybe more, (I have seen it on photograph, but there was no reference to compare), but it seems that while this watermill is functioning, one who has installed it did not understand principle on which it work, as turbine is suspended over the creek, instead of using water to fall on turbine, which would IMHO extract more energy, and same turbine would be able to be used as water pump.....

I dont quite get what OP is intending to do, as once he mention compressed air, then steam, and all for purpose of replacing electromotors by turbines....?

If effective fuel use is all that is intended, then I would in his place just reconstruct Tesla motor, of course, using better materials to avoid problems Tesla faced in his time. I am sure that Tesla was teling exact results he has achieved, because he has had no reasons to falsify results, and surely they would not grant him a Patent for this, because he has had to demonstrate that his invention work as described.

Unfortunately, lot of people think they are more clever than Tesla, so they start at once by making >>improvements<<, and I would say they did not even grasp basic idea behind such invention, and here it is use of one neglected natural force of adhesion and fact that angular velocity is same only in number of degrees by which wheel or disc turn, but that lenght traveled is square of radius multiplied by PI, so fluid has to travel shorter way in same time unit, which is perfect for fluid that has lost half of its kinetic energy, but would still be faster than speed of rotation of discs at smaller radius........

All Tesla's patents have become public property long ago, so anybody can manufacture any of them without having to pay royalty, so why dont people just take treasures that great engineer has left to mankind, instead of calling him names and thinking they are more clever so they would improve on his work?

I dont say there cannot be improvement possible, but time for improvement is when one has in hand something that work, as more offten than not, what we think that would improve something can violate some basic principle that makes thing work, so we would get opposite from what we intended to achieve. Here, discs has to be thin to be able to put many in small space, and what work is surface of discs and fluid adhesive force, so making bigger spaces between them and forcing fluid at high speed inside would not work as expected, mark my words :-)) Puting obstacles in fluid spiral path would not improve thing either, and if Tesla has put something on plates, it is more likely that it was intended to help to evacuate fluid from turbine then to provide something for fluid to push upon.........

Whatever I do, I first study how something work, and when I am sure that I understand this, and I have reproduced originall results, then I start thinking where improvement could be made. I would say that in inventions like Tesla's turbines, probably only materials and workmanship could be improved. In my country, where Tesla was born, engineers and physicists have been puzzled for decades by this same turbines, as both groups claimed that such turbines should not work at all :-)) Unfortunately for their peace of mind, they have had working models in hands, so they canot just dismiss that as hoax or clever trick, and moreover, anybody following Tesla's engineering plans was able to get same results, with >>impossible<< efficiency of 95% that is disprowing unquestionable validity of Betz Law...........

Some have criticized me when I wrote that Betz Law work correctly only for given set of parameters, so it may not be valid with parameters changed.....

Tesl's turbine is proof that it is so, and I would be very grateful to OP when he publish results (specially that part about efficiency of energy conversion) when his project is finished and working.........

Sorry if there are spelling errors, I could not check it because CR4 spelling checker reported some error and then fell into endless loop.........

Regards from Zagreb, the capitol of Croatia, Europe!

Marijan Pollak, IT SA/SE 1st. Class, Instructor and Team Leader (retired)

Henrik14,

Greetings from (near) Albany, the capital of New York, USA!

It sounds like we are "on the same page" as we say here in the US.

What I am trying to do is use Tesla's brilliant design to build a steam turbine unit that can be used as a direct, bolt-in replacement for the electric traction motors in a diesel-electric locomotive. The diesel prime mover will be replaced by a high-efficiency biomass fueled steam boiler. Even if I can't beat the diesel on efficiency, if I can beat it on total ownership cost per horsepower-hour, the project will be viable.

This will be a direct-drive turbine, no fluid couplings between the turbine and drive wheels. So I need to make sure the turbine generates as much torque as possible from zero RPM. This problem led us to discard a couple of more modern designs (along with the fact that we can produce Tesla units ourselves.) Yes, I could add in a fluid coupling and/or torque converter unit, but that would greatly increase cost, maintenance, and complexity.

With RPM at zero, I want less velocity of steam, but more volume, to produce more torque. As you described, in this situation the steam might make fewer spirals (less efficient) but flowing more steam makes up for it. As RPMs come up, I need the nozzle to flow less steam but at a higher velocity, to maintain the 2:1 ratio between the steam velocity and the angluar velocity of the rotor. I'm hoping the Aerospike tybe nozzle will do this automatically rather than needing an adjustable nozzle- if so, that will save a LOT of complexity. One point of this whole project is using what we in the US call the "KISS principle."- "Keep It Simple, Stupid!" Every moving part that we eliminate is one less we have to manufacture and install, and one less thing to go wrong.

The end purpose of the whole project will be to have woodchip fueled locomoitves (cheaply converted from older, polluting diesel-electrics) pulling trains of woodchips from the forest to the power plant or biorefinery, and doing it cheaper and more reliably than anything else on the market. Zero petroleum consumed, low emissions, quiet operation- oh, and 100% of the carbon is offset, also.

Honored coleague,

I wrote for an hour or two and then all disapeared because of broken Internet connection :-))

So I would just repeat one suggestion to you, that would make things still simpler for you:

I would put instalations that would turn wood chips into Biogas at place of their manufacturing, and produce liquified Biogas/Methane that could in turn be used as fuel (even in your locomotives) or to produce more valuable products like fertilizers, composite glues and bioplastic. That would make less quantity and more valuable products for transport, and you can skip over steam production and use Tesla's motors instead, using liquified biogas.

What do You think? Are we still >>on same page<<? I hope so........

I work on new windpower and solarpower stations, and could at this moment just enwy you because you have financing available to realize this project, and I have none.

But whenever I mention this on CR4, I stand to be criticized like I want to peddle something, and nobody see that my invention mean lot of cheap electricity, which should lessen demand for other forms of energy, specially fosile fuels, and that cheap electricity would make any product whose production is using it, cheaper and so more affordable, which means more would be sold, production would rise, people would get jobs and salaries instead of being unemployed, and they would then pay their mortgages so there would be no insolvent Banks nor impowerished Insurance companies, which all has made up this worldwide financiall crisis.......

I hope at least you agree with me that I am not after being stinking rich, but want to help all people like my countryman Tesla have done :-))

Regards, Marijan Pollak

Henrik14,

I had thought about using Pyrolysis oil http://en.wikipedia.org/wiki/Pyrolysis_oil as a substitute for diesel fuel.

However, this project wants to not only go "green", but also to eliminate most of the expensive, unreliable parts of a diesel-electric locomotive, replacing them with parts that can be easily repaired rather than having to purchase new or rebuilt parts at high cost.

Our target market is the small railroad which is currently using old, worn out, polluting 1st or 2nd generation diesels, and is getting eaten alive by fuel and maintenance costs. 250 gallons of lubricating oil for an oil change! Several gallons of diesel per hour at idle! The cost of the environmental cleanup for spilled petroleum from one derailed diesel locomotive can break a struggling railroad.

Our target fuel for these locomotives is either wood chips or commercial-grade wood pellets. We prefer wood chips since they are inexpensive, and are expected to be one of the major commodities on the rail line we want to lease, once we have motive power that won't bankrupt us.

Ing. L. D. Porta's work on steam locomotive development inspired this project to a great degree: http://www.trainweb.org/tusp/porta.html He greatly increased the efficency and power of steam locomotives, and pioneered advanced water treatment that practically eliminates "water side" problems and reduces maintenance to a "blow down" once or twice a week and a cold washout once or twice a year.

While I would prefer to build a "conventional" steam locomotive, the project is much more likely to be funded and find customers if the locomotives look like diesels on the outside. Also, rebuilding a diesel "hulk" is much cheaper than building a new locomotive from scratch, plus the chassis already has all required safety systems in place.

Once we have the profits from these units coming in, and the factory space already paid for, we plan to build reproduction steam locomoitves for the tourist industry, using the best modern steam technology to drive ownership cost per mile down below that of the old diesels some of these lines run. Then, with two proven products under our belt and the performance data from the reproduction locomotives, then we can think about marketing Modern Steam locomotives.

Another part of the plan is marketing a "sustainable technology" version of this locomotive overseas. Instead of the automated boiler controls and multiple unit capability, they will require a fireman to monitor the boiler. A country that needs rail transport but can't afford or support GE or EMDs gee-whiz computer controlled wonder locomotives should be able to maintain and repair one of our locomotives themselves. I expect these locomotives to be able to earn back their cost of capital even in the poorest countries and the worst economic conditions. We make money when our customers make money, who make money when their shippers make money, who prosper and create more jobs and prosperity. This raises the whole economy so I can sell even more locomotives and transport more products by rail, getting even rich in the process. Then I pour that capital back into more cool projects that just happen to be "green". That's the plan, anyway.

Hi Mark Stockman and Henrik14

I've been following this thread with considerable interest.

The idea of using the steam turbine equivalent of a series wound DC motor has been in my mind for some time. Fueling the boiler with wood chips seems a great idea.

The Tesla turbine works as a radial flow turbine. Close spaced discs allow the impeller blades of a conventional turbine to be eliminated because viscous friction drives the discs.

If driving with compressed air, a tangential inlet followed by a fair clearance between the casing and impeller discs allows the incoming air to adjust the path of it's spiral according to flow rate, gaining speed to conserve angular momentum. This avoids the need for airospikes and similar geometric complications.

If using steam, unless the steam remains superheated for the entire journey through the discs and exits still superheated, water droplets will rapidly erode your discs to nothing.

This occurs because condensed water is denser than the incoming steam so centrifugal forces will throw it outwards to where it is balanced by the incoming steam velocity. The net result is that the water can't exit and keeps getting thrown against the discs, eroding both by impact and possibly variations of cavitation forces, until the heat generated turns it back into steam.

This is very much simplified, but as far as I know, the only effective radial flow steam turbines are outward flowing, not inward.

The other point to consider is that an inward flow radial has a decreasing cross sectional area. If it enters at supersonic speed, that will slow it down, with a complex collection of shock waves forming which will be expected to generate considerable vibration and disc oscillations, unless you have very rigid discs.

I like the Tesla turbine design, and I would first make a test one (as Henrik14 suggests) exactly like Tesla's original design to establish the "wrinkles" involved in it before you start modifying it.

Unfortunately, the best bet for a steam turbine is likely to be an ordinary impulse turbine or even a reciprocating engine.

With modern design and materials, I think a great reciprocating steam engine could be built quite cheaply.

Supersonic speed of steam? Not likely and surely not necesary. One hundred years ago nothing like this was used, else they would have to develop theory of supersonic fluid movement and shockwaves generated by breaking sound barier :-))

Tesla motors were using internal combustion, and there was no way to cool disc plates, which resulted in occasional buckling that deformed plates. Material science produced much better materials, and recently also near perfect insulators are produced. If water would seem to be problem, there is good stainless steel to be used, but Tesla recommended very dry steam to be used. Just there is need to follow his engineering plans literaly, but it would not harm to use better materials to prevent problems he also described. Water in steam is mainly problem (IMHO) because steam exit trough holes situated on plates near axe of rotation, and water would be thrown out and come on bottom side of motor cavity. Steam is slightly better than fuel burning directly because its temperature drop while kinetic energy is extracted, so there is no overheating possible, but then steam generating system is less than 100% eficient, therefore I would choose Tesla motor with internal combustion. As I wrote in previous post, it has much wider field of use, and there steam production would be just big problem that take lot of space and lower overall efficiency of fuel use.

Othervise, I agree that much better steam reciprocating engines could be built presently, but generating steam has its requirements and fuel takes lot of space.

I hope Mr. Stockman would understand my arguments and do what is beneficial for greater number of people, not counting obvious fringe benefits of more efficient fuel use, even if diesel is still continued to be used.......... untill replaced by Biogas or Biodiesel, whichever prove to be easier to produce and be cheaper, with less polution produced in use.

Few steam locomotives for tourists cannot do much harm, even if fueled by coal, like in old times......

Raising fuel efficiency of fuel use from 46% to 95% would save at least half, so if all diesel locomotives would be converted, that would be grat savings, but diesel is used in cars and trucks and boats (at least in fishing boats), and beside saving fuel Tesla motors require less space and weight less, and are far simpler to maintain while I would say they require no servicing, no oil changes like it is necesary in ordinary cars, no piston rings change or motor block refurbishing, and speed depend on supply of fuel, which is easy to regulate. So total cost in use is far less then with classic engines using Otto cycle (reciprocating engines) and they should last far longer.....

I would dare to say that compared to clasic engines, Tesla motors are fail safe because there is much less parts present, so if there is fuel to burn, they would work.....

Only better thing would be Tesla's electromobile, secret of which was probably lost or hidden, because source of its energy was nearly free........ Once I earn some money on my inventions, it would be my main goal to reconstruct it, as its power source can be used nearly everywhere, from houses to airoplanes.

How is wind available in Australia? I know you have plenty of sunlight, so you can produce lot of cheap electricity, and with my water condensation devices of agricultural capacity, there could be much more food grown, or at least forrests and meadows. Therefore please keep in touch, as I hope by end of year I would have patents granted.......

Skeptic wrote:

"I like the Tesla turbine design, and I would first make a test one (as Henrik14 suggests) exactly like Tesla's original design to establish the "wrinkles" involved in it before you start modifying it.

Unfortunately, the best bet for a steam turbine is likely to be an ordinary impulse turbine or even a reciprocating engine.

With modern design and materials, I think a great reciprocating steam engine could be built quite cheaply."

Skeptic,

Thanks for the feedback. Actually, I have designed (on paper) a unique reciprocating steam engine. Two HP and two LP cylinders, two moving parts (not counting the valves, etc.) It's scaleable/gangable, so you could have a unit with six HP and six LP cylinders with the cranks set at 120 degrees, with only four moving parts.

It just doesn't have the power density for my application, though. It would be better suited to a modern "steam lorry"- using some type of steam generator. The emission controls on the current generation of on-road diesel engines have increased cost, decreased reliability and cut efficency. Heat is a problem also, as the EGR engines run hot- no problem, increase the size of the cooling system, but there goes more thermodynamic efficency.

If somebody is working on a steam road vehicle, I would be glad to share the design- for a small percentage of net profits and my name on each engine.

I see........

Just there are problems like availability of material to burn (in other places or countries) and sheer quantity required to feed if woodchips are used, not to mention that they have to be dry enough to burn. In your place I would rather make false steam locomotives than really use steam as energy source, and there is many sources for production of Biogas, which could also bring prosperity to owners of such instalations, not to mention that it could be used in cars, trucks, agricultural machines, boats and for cooking, heating..... Spill out would not require any expensive treatment, so any loss would cost as value of gas itself, and this ought to be cheap, considering it would be made from vaste materials that are also ecological hazard in some cases.......

Pyrolyse was used by Germans in WW II, so it is proven to work, but in biodigestors there is no waste from process, and you dont need to dry chips to be able to burn them, so freshly made chips could be used, and in fact they are better so less water need to be added. Fact that you need to spend energy for heating wood is telling it is more expensive, and it is not easy to make process continous and prevent loses in process.

In regard to diesel locomotives, I would say that there is enough space so you can put Tesla motor instead of each electromotor, and then you would have fail safe locomotive as it would be able to run with any pair of motors functioning, and at full load of course you can use all motors at once. I have idea how you can use same motor for forward and backward movement, if it is Tesla motor, of course.

As I wrote before, it would be more ecconomic to transport less frequently more valuable products, but if transporting itself is source of your income, then perhaps You would want to do it frequently. Yout mind your economic, as that would be low cost materials as wood chips, so transporting them would raise the price. If I would be in your place, I would aim for replacing as many diesels by Tesla motors, as even if diesel continue to be used, it would require less of it, and if what I read is true, those motors can run on anything that can burn, provided it is in liquid state. Then keep in mind that Methane could be produced even from coal, and countries where they have earth gas in quantity could use it also. But beside using as fuel, methane could be turned to fertilizers for agriculture, and be used in many other usefull ways, so IMHO there should be promoted its production, not just for your locomotives. Last of all, Methane could be produced from CO2 and hydrogen from air, which would capture CO2 at least temporarily, provided there is cheap electricity available, but such process could serve as energy storage as well, disposing of need for batteries or power lines conecting to remote places where it is not economicall.

Really, dont you think that it is easier to produce steam just for effects in your reconstructed steam locomotives, and such system could tap waste heat from Tesla motors, too, and save on fuel that produce steam........ But if you need to have 3-4 persons shoveling woodchips into furnace for effect, and as many wagons of woodchips to be burned, then have it your way........ As far as reconstruction of steam locomotives go, it would be enough that old models be made with new materials and more exacting workmanship so fuel would be used more economically, but there is no great benefit to the world in general, like it would be if Tesla motors were used, because of their power density and ecconomical use of various fuels because of greater efficiency.........

I use simple rule when deciding what is better: it is design that benefit greater number of people!

So, that is my opinion, and please consider it, as primary goal should be to use fuel more economicaly, so there would be need to burn less of it.

Not to forget that same motors could be used for production of electricity if conected to generator units, and there also it would benefit the World if fuel consumption would be made less, and wider variety of fuels can be used, no? Therefore, once You develop good Tesla motors, you can even start replacing classic automobile and other wehicles motors, no? There to have steam would not be practicall, so consider wider picture, and then you would be king of Tesla engines, known all over the World.......

Less moving parts and therefore simpler maintenance, as well as cheaper engine would surely be popular in poor countries, so you could even sell production licenses and get rich on royalty, and have time for tinkering at your hobbies, while making business in remaking locomotives and cars, trucks, tractors and electricity production units........

Yes, KISS it, and like ugly frog it would turn into enchanted princess :-))

Regards,

Marijan Pollak

During WW2 petrol was rationed for civilians and some towed a trailer behind their car with a "gas producer".

Basically this used coal (I think coke was preferred if available) with air run through and a little water to produce H2+CO. The water not only provided H2, it also kept the temp from climbing too high.

It should be feasible to use wood chips in a similar way to produce "water gas" (No not HHO! Different animal) and use that to burn in a modified diesel (cheapest option probably) or make up a Tesla compressor and turbine to combine as a gas turbine.

BTW, one of the notable features of the Tesla turbine was it's very high running speed. This was one reason for it's spectacular power output but in this application it would call for a sizable fixed speed reducer on the drive.

If used as a gas turbine, it may well need a multi speed gearbox, depending on the torque/speed characteristics of the turbine.

Mark, if those spacers are put there it is most likely to keep plates from buckling by keeping distance between plates fixed. As I see it, they would better be presenting thin edge to blower, as that would minimize turbulence created. Also, number of them should be minimized, and optimally perhaps three sets would give enough support. But due to 0.4 millimeter gap between plates, other shape than round would not be practical. In the end analyse, I would say those should be avoided if at all possible, as they may cause vibrations as well because working media would hit them intermittently so fluid flow would not be as uniform as it can be..........

Somebody mentioned that there would be turbulences created between media that flow at different speed, but I believe that would not be the case. Point is that working media is traveling in same direction, so in boundary area there would be layer of media with middle speed, or rather such where speed of faster layer would be gradually decreased and that of slower layer gradually increased, and in exact middle there would be some middle speed established. But due to small gap between plates, area of contact between spirals of higher and lower speed is minimal and I believe it could be safely ignored. If speed difference is high then higher speed spiral will just slide over slower speed spiral. No turbulence could be created because higher speed media is constantly pressing over lower speed spiral pushing it inward, therefore vortices cannot form in it, specially because direction of movement is same. One possible cause for buckling of plates that marred functioning of Tesla motor could be higher pressure of working fluid entering between plates, but that should not happen if working fluid is supplied at constant speed and uniformly over all plates, as pressure should be equal from both sides of plate. Only exception to this are end plates, so it would be good idea to make them much thicker, what somebody already suggested.

I again apologize if my thinking is faulty and there are some experts that know better what is actually going on in Tesla turbine then me.....

Turbulence would not be a problem between plates as you are within the boundary layer, so flow cannot eddy and is basically kept laminar.

In a large turbine, the Reynolds number could rise high enough to have turbulent flow, but full turbulent flow couldn't develop, as flow would still remain boundary layer controlled.

Spacers will interfere with performance at part load and overload. The lack of spacers allows it to "select" it's own spiral path through the machine regardless of load, giving good flexibility of operation.

The design is one where disc friction actually works for you except at the space between the end discs and the cover. Because of this, increasing the number of discs will improve efficiency, although the number is dictated by the load and disc OD.

I'm still dubious about the design for wet steam, but it should be good for compressed air, gas turbine compression and turbine and high pressure (superheat) stage of a multi stage steam turbine.

It could be used as an outward flow turbine for wet steam, but I think there will be serious reliability problems for inward flow.

Hi, Sceptic,

I am glad that at least someone agree with me... at least I think You do?

I dont know about Reynolds Number, but someone mentioned even excess speeds, which I think absurd.

As much I understand how turbines work, speed of turbine is usually half of speed of fluid that is powering it, and cannot be higher than that, unless in case where turbine would also compress fluid and thus make it flow faster.

I wonder what comments would be when I patent one such turbine :-))

Been talking to LMS representatives and when I have shown them my small prototype, they were concerned that turbine would go supersonic. I know that cannot happen, because I plan to design it backward: first, since I know generator I plan to use would work best at 2500 RPM, I would make design optimized for such speed. When I know how much air and at which speed I need so turbine can achieve this RPM, then I would adjust my whole system to be optimall and provide constant air speed and volume for turbine. Originaly I planned to make system that would simply let surplus wind pass trough it, but if stronger than average wind is frequent, and there is lot of usable wind under average speed, then it would be ecconomic to install 2,3 or more turbines, where system would use one turbine in low speed wind, and then as wind speed increase, other turbines can be switched on, one by one. There is only problem of increasing wind supply on first turbine, but I think it would be regulated by size of pipe that would feed airstream to it, as higher air pressure would open door in main, greater sized pipe, leading to next outlet for second turbine and doors of third compartment and so on. After last turbine there would be door leading to windfall side of system where surplus air would be let out of system.

Can You coleagues tell me if there is any reason this would not work?

That way wind itself would regulate its use, and even strongest wind cannot be a problem, while most of economicaly usefull windpower would be extracted. Once there would be cheap generators due to mass production, it would be increasingly ecconomical to use multi turbine systems, and also this kind of plan allow owner to install turbines one by one, if there is not enough money to buy them all at once.

I am also concerned about height necesary for my Windpower Stations, as I have found some Windmaps showing that at 80 meters height there is less than 5.9 m/sec wind allmost everywhere, but I would rather have less high structures. Does any of You have Windmaps for height of 40 meters above ground or less?

Regards, Marijan Pollak

Hi Henrik14

For any available wind, pressure =0.5 * rho * (v squared).

For any normal wind speed, it is unlikely you will get enough available pressure drop to drive a Tesla turbine, or any other radial flow turbine.

There are a number of vertical and horizontal axis wind turbines which are quite efficient and reasonably priced, but mass production of standardized turbines would reduce cost and make them more practical.

In some circumstances, using a duct to accelerate flow and concentrate it onto a turbine may have merit, but the cost of the duct and the need to keep it turned into the wind would tend to make it more expensive than the present way.

Why not mount a couple of horizontal axis machines on top of the earth wire extensions of the ubiquitous EHV towers distributing power through the grid?

These could be mass produced to reduce their price and replace and even supplement the power transmitted through the grid.

Dear Sceptic,

Browsing trough database of the Patents recently I have found great number of patented Windpower stations using ducts which compress and therefore speed up, even guide air into making artificiall vortice which speed up air considerably. Therefore it is usefull and working principle which can be used to our advantage. So if adequate air speed is only problem You see, it can be achieved, and is not so costly as You may think. Even bag of sailcloth can be used to do this, and it is light and relatively cheap. As for turning unit into the wind, just common vertical tailplate is enough, anfd if it come to this, again sailcloth spanned over the tail frame can be enough and very cheap and light too. I hope You agree with me so far......

What those systems allready patented lack is self regulation of air volume supplied to turbine (and, o, Boy! I have seen all imaginable type of turbines used, all supossedly working, but not necesarily eficiently. Lucky for me, it seems nobody so far has invented same type of turbine I intend to use, and nobody tried to use Tesla's turbine either) and neither they have protection from the strong wind, which my design incorporate.

In regard to Your idea to use high voltage towers for supports of horizontal axis turbines, same problems of undulating movements of such turbines support in strong wind due to sail effect, together with turbulency created that would surely shake wires seems to me reason why this is not practicall idea. That such towers would be better support for such turbines than those pipelike supports in contemporary use, that I agree with You. Engineers constructing them in past have faced same problems of sail effect as constructors of contemporary HAWTs, so something could be learned there, which is worth knowing. Such constructions as those high voltage towers let wind pass trough them instead presenting obstacle to it, and construction is light but strong (like Eifell tower in Paris) and made out of relatively short segments that could be transported without speciall wehicles and built on site without using cranes, even by hand tools using screws. That is what I would use in my instalations as practicall, specially for poor countries without high technology. Anybody can make such segments form metal pipes using hammer, anwil and drilling machine, at least I think so, if I am not mistaken..... Heck, even I could do it :-))

All that is neded is proper building plan to get final shape that would function as required. As to how should optimall construction look like to be light and strong, we should look to nature for answers, where optimal constructions facing same requirements have evolwed trough bilions of years, and surely we cannot make anything better, can we? There are some species of cactus plant called Saguaro, that grows very tall, but withstand strong wind sucessfuly. My father was growing cacti of many kinds, some resembling Saguaro in shape, and after one winter some of them froze and died, I had chance to see how they look inside, and I marweled at network of crisscrosing upward spirals of their internal structure. I would surely borrow this naturall design for elastic support that is light and strong at same time :-)) I am sure that authors of >>Geodesic Dome<< have been inspired by similar natural constructions.

Same kind of examples could be found in nature everywhere, if we look carefully, and those are allready strictly optimized constructions and shapes. I need to just apply materials at my disposal to imitate such naturall constructions, and I am quite sure they would function as expected, so I would not need to build severall prototypes and find what work by trial and error, as some people suggested to me. As for ideas of my own, in regard to my turbine, I have built little prototype and it works even if very crude and not optimized yet. For other things, I believe that we should use trreasury of ideas left to us by engineers of past and be humble enough to not think we are smarter than them and could at once improve on their design. I have read recently that some people have built devices according to originall plans made by Leonardo Da Vinci, and have found them working properly..... So is, I believe, case with Tesla turbine, so whoever is atempting to build it should first make it according to originall engineering plans that Tesla made, using common sense in choosing materials from which to build it, and if there was known problem with design, like that of buckling plates, then we should look how similar problems were solwed by engineers of the past, and apply those solutions. One example with circular saws was allready mentioned, so perhaps same solution can be applied, unless there are some holes in such blades that cannot be on plates of Tesla Turbine. Actually, only requirement of Tesla turbine is constant distance between plates and their uniformity (as I see it) so perhaps we can prevent buckling of plates if we do it first :-)) So, there is idea: instead of flat plates, half dome shape could be used. If centrufugal force would tend to straighten those plates, they would all straighten equally, thus preservering gap between plates, and this is all that is important for its functioning. But then, perhaps something vitaly important could be changed the way it should not be, and thing would not function because of this, or I chanced on only improvement that would remove plate buckling problem and even make thing function better, who knows.... That is why I need good Virtuall Prototype testing program, to be able to test such ideas that occurs quite naturally for me, but somehow are not occuring to anybody else I know.

I tries recently some programs that are supposed to be among best, such as ANSYS, and have found them inadequate to puropse. Therefore I beg any of You to supply information which is best program for building and testing Virtuall Prototypes, if any of you have tried to use them. I believe using such program is cheaper than making prototypes in most cases, with exceptions of programs such as LMS CAD which cost 50 to 100 thousand Euro, and have learning period of 24 months, according to their representatives I spoke to. But I think something must be wrong with program that one has to learn that long to be able to do things properly, as it is obviously did not made with end user in mind, what do you say?

So, please help if You can, so I can concentrate on programs that work instead of wasting my time on those which are useless to me as inventor who is not also expert in the field and dont know formulas by heart!

I apologize for any spelling errors, but CR4 speling checker fell into endless loop and after waiting half an hour I lost patience and canceled it :-((

Regards,

MArijan Pollak

Hi Henrik14

Even bag of sailcloth can be used to do this, and it is light and relatively cheap.

Good idea. For some reason my thinking had locked onto steel or similar rigid materials, but of course they are not completely necessary for this job.

My point about using a Tesla turbine for this job is that it is basically suited to a high pressure drop, whereas wind is an inherently low pressure drop source, although there is a lot of it available if you can capture it over a big enough area.

When I was designing EHV towers long ago, they were made of angle bolted together.

I once supervised erection of a 20m high radar tower which was also made of angle using friction grip bolting. The rigidity requirements for that tower were quite demanding, but it was readily achieved.

EHV towers are usually quite rigid and would be a good base for a wind turbine. Of course the earth wires would probably be mounted above the turbine, which would provide very good shielding for the tower. (If placed below they would be as effective as normal and it may prove mechanically simpler).

The partly erected tower was used to support a gin pole which was used to hoist the materials needed to the top.

Same construction and erection method was used for the big TV transmitter towers.

So, you agree with me, it seems :-))

I hope You understand now that my design is sensible one and that I can deliver what I promise in other regards also, specially in case of turbine that would be more effective than Betz Law predict as absolute maximum.

At that, I would say that Tesla Turbine has already proven that it is not so absolute as some colleagues stated, calling me fraudster and telling I insult their intelligence by stating this is possible...

What do You say, is Tesla turbine breaking Betz Law by its efficiency coefficient or not?

Regards, Marijan Pollak

Betz law simply states that 65% of the kinetic energy in wind is available for use.

Extracting beyond that leaves the exhaust moving too slowly to satisfactorily clear the turbine and merge with the surrounding air stream.

This is a highly simplified explanation, but should be close enough.

Betz law is not an absolute and it may be possible to go beyond it without breaking any fundamental physical laws, but you would be well within an area of diminishing returns.

The maximum velocity you can get from "funnelling" wind is dictated by the dynamic head of the undisturbed air stream. Off hand I'm not sure what gain you can obtain before air starts bypassing your "funnel". I'll have to think about it, but there will be a theoretical limit as well as a practical one.

The practical limit will be when the amount bypassing (due to a build up of back pressure) becomes too great to allow any further worthwhile gains.

As the energy in the wind is free, losses due to bypassing are not serious until they become quite large.

Dear Sceptic, I saw various values for turbine maximum according to Betz Law, but most agree on 49%, which I think is reasonable since bare turbine without using any tricks would not be able to extract more, because as You say slowed down air start to present obstacle to normal air flow so wind pushing turbine must push that slowed down air also to be able to pass trough, and that cost energy in size of half of the difference extracted by turbine. Since this slow down the air stream, less energy can be extracted by turbine. So either space behind turbine should be greater in volume so slowed down air can spread in this space and continue going out in slowed down speed, or some additional air streams emerging trough nozzles behind turbine and facing toward exit should be used to wash out slowed down air lending it new energy.

That could be that same air that would start bypassing funnel, or just air flowing by it.

I believe that if things are optimized so that wind can only compress and so speed up air already in the funnel, then there would be no bypassing of funnel. Things could be made to make artificial vortice inside funnel, and that way air start passing trough much faster then without it (it is already been patented so I know it works), and also whole system could be made to simply open when air pressure become bigger than funnel can handle, and there would be no bypassing as surplus air would went straight trough funnel. It would also be regulated by wind itself. Best is, trick is in proportion, so any speed of wind would behave same, because presure of it in wider part of funnel would allways be great enough to speed up air of deepest part and so push it trough narowed down part of funnel. Since energy cannot be destroyed, in this case it concentrates. That is I believe how hidraulic systems work. I have theory that pressure in static media is distributed within vessel equally in all directions, but if fluid is moving, then presure in direction of its movement is greater then on walls, as long as there is no obstacle on which this increased pressure can ram.

But I asked You if You agree that Tesla Turbine is beating Betz Law or not, and You don't want to commit yourself on that.....

I think it should be obvious, if from spiral to spiral air slow down, but angular distance it has to travel gets shorter faster than slowing down of its speed, so still on each next spiral it partake of some (and I would say half) of remaining speed, therefore in 5 spirals even 98% of kinetic energy can be extracted....... After this, trick is to provide enough space for slowed down air or steam as I described before. That is why Tesla turbine has so big holes near axle. Since all those air spirals continue to push air in the middle, surely there is artificiall vortice formed, and this make air go out faster than is expected. But there is axle in the middle, and I believe if there would be pipe instead and air streams could get in trough holes made that way so fluid from its spiraling path enter inside without encountering obstacle (if for instance there is just slot lenghtwise on this pipe, wide enough so one spiral can enter easy), then inside this pipe unrestricted vortice would speed up fluid still more.....

When I would have some good CFD software that could model this, I would surely try it to see if it is just my imagination or it would wield better results.....

Some people mentioned there would be temperature problems, like temperature would be accumulating, and according to Law of Entropy it is not possible. If anything, slowed down fluid is also colder, is that not so? At most, temperature can be that of fluid at full speed, right?

I mentioned idea about making half round (or better say half globe) plates instead of flat, but You don't comment on it also.... :-((

Please, I would really like to know what You think about that!

Regards, Marijan Pollak

You could well be right.

Certainly if there is enough head in the air to run it, it has the potential to beat Betz law, which, as I commented earlier, is not a fundamental law of nature but basically a practical limit for normal wind turbines.

Yes, that is what i tell all the time: Betz Law is valid for set of parameters that are assumed for ordinary kind of turbines, but not for situations where parameters change or new parameters are introduced.

Thanks and may Gol bless You and us all!

http://gyroscope.com/TeslaTurbines/ makes tesla turbines, they say having a nozzel for each slit is more efficient. This should eliminate the need for thin blades.

Have you considered lps and eps as disk blanks

You remember those big black cds we used to listen to?

The spiral scratch could provide some interesting surface effects

Also are you aware of the smart drive TM genset/mag bearing in the drive of fisher paykel washing machines

im messing with a hydro turbine based on one at the moment

no moving parts ;P

Cheers

Tree planter

Hey gang!

A few quick things:

First, while the fuel input to the firebox will be wood chips, the fuel consumed is actually syngas using the Gas Producing Combustion System (GPCS).

Tesla's later designs incorporate spacers between the discs, at the edge and "at a sub-diameter". This reduces disc warping, and the spacers at the edge make it a hybrid between a pure disc turbine and a Pelton type turbine, increasing torque output at low RPM while preserving the benefits of the disc turbine.

Tesla also used both steam and combustion gas to power some of his turbines. A more radical idea I have been toying with is using a steam venturi to accelerate the flue gas (and create draft) and then feeding both hot exhaust and steam into the turbine. Thoughts?

O my Lord, I wrote answer to Sceptic and it dissapeared, then to you and got message >>Server did not receive data<<....

Fortunately I saved message text first, so I can try to send it again now......

I would build first one engine acording to original blueprints, then when it is tested to work as expected, You may make experiments and build modified models, leaving original as reference. It is good that Tesla motor is cheap and uncomplicated to build, so You can just change discs on experimental models to see if there is any improvement achieved. I would not try to use both hot exhaust and steam together, as pressure of steam can prevent exhaust from functioning even if pressure would be equall. I would rather design system so it could use this hot exhaust to preheat water for steam generation, if possible.

"I would rather design system so it could use this hot exhaust to preheat water for steam generation, if possible."

That's the current plan, pretty much. The combustion exhaust from the firebox will pass through an economizer (air preheater) and feedwater heater on its way out. The exhaust steam will pass through a low-temp ORC system which will drive the accessories, then into a loop in the condensate tank.

I want to use a closed loop system if I can manage it, or at least recycle a large percentage of the steam.

Something sily is going on, and I dont know what is cause......... Right now I wrote one sentence and it dissapeared, and before this I cannot get latest post before opening it in new window. First window was foreshortened to answer/post Nr. 6, second went as far as 21, and only in third window I can see your latest post........

But since I started using TELE2 Prepaid Mobile Internet, my computer is misbehaving, so perhaps this would be better when I change IP.

Now, I wanted to write that we are still >>on the same page<<, as I have plans to make >>closed loop steam turbines<< for my Solar Power Stations.

Provided of course that simulation software confirm that it is viable idea, and engineers from one 87 years old company that is specialized in making steam generators do not find some practical reason why it cannot work. Basicaly there would be two turbines, one working on steam that would be blown on it, (perhaps it would be Tesla turbine because of high efficiency or clasicall multistage steam turbine) and another working on condensed water that would be forced to lift by remaining steam pressure and then fall to another turbine. Only requirement would be to have two one way ventiles working on pressure, one after steam turbine leading to chamber with pressure lift system and another turbine. Next has to be on outlet for condensed water that would let out surplus water that condense from steam, and since condensed water would be hot, it would retain some temperature before comming to evaporation chamber where steam would be produced. Work of generator would be regulated by motor controled ventile on system that feed evaporation chamber, othervise system should work all the time, and this is not desired if acumulated solar heat is to be used on demand.

I wish I could have one machines engineer to work with me, to say at once if idea can work or not, and if not, why, so I could adjust design to include all parameters.

Well, I hope it would be soon, provided I find at least one small investor that would have fate in me :-))

Now, YOU are such engineer, so please tell me: could my idea work?

RE: closed loop systems for solar power stations

Let me see if I understand your idea: First the solar collectors vaporize water into steam, which turns a steam turbine. Then the turbine exhaust is used either to run a pump or a venturi to lift condensate, which then falls by gravity to a water turbine? I'm not sure the energy left in the steam after going through an efficient turbine would lift enough water high enough to make it worthwhile. But, they laughed at the Wright Brothers, too.

Why not use water (with automotive antifreeze) in the loop to the collectors, and then use a low-temperature closed loop refrigerant system (like the ones already being used for low temperature geothermal power) to extract the heat energy from the water? For energy storage, just use a large insulated water tank- the larger the better for thermal efficency.

That's the nice part about the closed loop Organic Rankine Cycle- it couldn't care less where the heat comes from, just that there's a heat difference.

Yes, main goal is to extract as much energy whichever way.

Now, to understand my idea You would have to know details of whole configuration, else it is hard to grasp. Of course that there would be little (about 5% or less) energy left in the steam, but using it over great surface of water should make it great enough to lift some condensate and let it fall over second turbine, but question is if this would be economical because of added cost and this of course cannot be used in small volume units :-(( My Solar systems would be modular, but some things could be centralized, like energy reservoir, condensate reservoir and evaporator system (that is, steam generating unit). Then if exhausted steam from hundreds of turbines is collected, total leftover would be in great volume of steam, so much greater discs on Tesla turbine would have to be used (because greater diameter, less energy is required to turn them, regardless of fact that overall speed would be small), and there would be much smaller number of secondary turbines, about 20 times less. Still, it may not be economically viable.

In regard to leeching heat out of condensate, it is not necessary at all, because that much less energy have to be added to water to produce steam again, don't You agree? I was thinking about further using remaining steam to help it to condense to water, and act of condensation would release latent heat and if caused by molecular adhesion to already condensed water, then this energy should raise temperature of condensate and energy is not lost since condensate need not be cooled before reuse.

That is why even classic steam turbines are very efficient presently, even if turbines themselves are not so effective if multi stage turbines are not used. They need just to be properly insulated to prevent energy leak as heat irradiation, right?

Are we still on >>same page<<?

Regards, Marijan Pollak

Yep! Still on the same page.

In my application, I want to use the former locomotive fuel tank as a condensate tank. This will be insulated of course. I plan to use the condensate tank as a condenser, rather than the atmosphere. First the steam goes to the turbine drive units (you understood that perfectly!) and then the usable heat that's left will go into a low temperature system to run all the accessories (air compressor, auxiliary generator, etc.) Without that, the leftover heat from the turbines would eventually boil the condensate, and I would have to start throwing valuable heat overboard into the atmosphere!

Nobody is shoveling any wood chips, unless we build low-tech versions for developing countries. Automated boiler controls operating an underfeed stoker. Not a lot of BTUs per volume of wood chips, so that is a design concern. For locomotives operating in mainline service, a switch to commercial grade pellets for fuel and/or a fuel tender might be necessary. Or (dare I say it?) coal?

Fine!

It is Your project, so surely in the end You would do it Your own way :-))

If You can usefuly extract leftover heat and use this productively, great, so

You do it!

IMHO, dumping of heat is not necesary in closed loop system, just heating

should be applied at same rate as energy is extracted from steam generated.

If You use fuel reservoir of diesel locomotives for condensation of steam,

where would You have steam generator unit?

Where would You put stove for new fuel burning?

Perhaps leftover steam could be condensed using still like system where

condensate would act as coolant because of temperature difference?

If so, then some heat would have to be dumped to achieve condensation difference in

temperature of condensate.

As I say, perhaps naturall tendency of water to connect itself to other water

moleculas (and there is plenty of such on surface of condensate, no?) would be

enough to cause steam to condense, heating condensate some more in process, so

when hot condensate is fed to steam generator, there would be need for less fuel

expenditure to produce steam again.........

At least it is my unprofesionall opinion, so tell me if I am right or wrong?

Regards, Marijan Pollak

The existing locomotive fuel tank is underneath the frame between the trucks (bogeys). The boiler (probably a hybrid fire tube - water tube design) will be above the frame in the space formerly occupied by the diesel prime mover and main generator. The space in front of the boiler will be for control systems (since that's where they are now) and everything behind it is fuel storage.

Yes, I plan to use a closed loop and exhaust the steam into the condensate tank.

If I use the steam exhaust to create draft in the firebox, then I lose the heat in the steam, plus I have to keep supplying more water and treatment chemicals. But the more I increase efficency, the longer the range for a given volume of fuel, and the lower the total cost per horsepower/hour.

Hi Mark,

I would send this yesterday, but after sending I got error: >>Server did not receive any data<<, and >>Message field should not be empty<< :-((

I saved message before sending as this has happened few times allready, so there it is:

If that idea of using steam to make fire burn stronger would make temperature in fireplace higher, that You would not lose any temperature with steam, as it would not only be recycled but would repay itself in higher temperature produced, no? But of course You would lose water in steam used this way, and this has to be replenished.

Cant You use destiled water and avoid use of chemicals? It would be easy to produce destiled water using Solar stills, so it would not be expensive......... Also, which chemicals do You intend to use, for what purpose?

It is good that You figured out where to put new systems, just make some drawings and check how this would work, step by step, so You would see if something vital could be missing, or some conection from one subsystem to another dont drop out by ommision or oversight...

It happens that people dont think much about parts or systems that must allways be there, so those are taken for granted, and assumed present while they somehow went out of sight :-)) In Skopje during 60's they made new hotel, and only at opening ceremony they discovered that nobody can enter it since there was no entrance! To make things worse, even stairs were not included anywhere, so there was considerable embarasment and delay in opening it, not to mention cost of breaking holes in floors and front wall to rebuild it and make missing features anew.........

What I cannot understand is that even workers building it did not find it unusuall to notice lack of stairs and entrance, then their overseers must have been blind, or they were so trained to follow orders without thinking so they have given up any independent thinking....

Yes, exactly my point: as high eficiency as posible so smallest possible loss of energy in conversion. Because of this, I would leave steam systems out alltogether and use Tesla motors and Biogas for fuel, like I wrote before, specially since this would be produced more and more in future, and from waste materials or even garbage, and that can be found everywhere, no?

Kindest regards,

Marijan Pollak from Zagreb, capitol of Croatia, Europe!

If we were using a different type of fuel, I would add steam to the underfire air, to keep the firebed cooler and help gas production. But with "wet" woodchips, there is plenty of water for this purpose. With the gas-producing combustion system, the over-fire air is designed to mix with the gases being driven off the fuel and combust in the upper firebox/combustion chamber. L. D. Porta designed a cyclonic firebox for his 3rd generation steam locomotives; we may look at this later, but right now pre-engineered "package" boilers are available for this project.

The water treatment we plan on using was also developed by Porta, and is being sold commercially: http://portatreatment.com/

We (as a company) are not quite ready technology-wise to make the leap to gas turbines- give us a couple years! We do have a certified pilot, aircraft mechanic and diesel mechanic (same person!) as part of the team.

Right now in the US, there is a lot of money being offered by the Government for increased thermal efficency in ground transportation.

Somehow I dont understand You: do You know that Tesla engine/motor, that is based on Tesla turbine can use as fuel equally liquid and gas, so there is nothing to research about. For technology that enable prodution of Boigas, there is one international group of engineers working on APIX SEP projects and technology is provided by company AgroBiogenic from India.

Next, wet woodchips are not good as they refuse to burn, and IMHO You need to heep as high temperature in fireplace as possible, not cool it down, specialy considering low caloric fuel like woodchips. You can use steam to force air into fire, but water from woodchips would be forced to steam much slower, as it has to boil first and that use temperature allready existent in fireplace......

Even so, if woodchips are containing over 30% of water, and usually it is 60% in fresh woodchips, then no burning is possible.

I am not technicall engineer, but that is my experience with kitchen stowe we had long ago....

Dont forget also that energy would be spent to produce woodchips in first place, so that should be added to total energy expenditure, right? Some energy would then be spent to transport chips to train, and if You also plan to transport woodchips across the country, consider how many times train should go back and forth to transport it to users, while liquified Methane would require less transport frequency for much greater value. Dont forget also that train dont go just in one direction (unless we have circular route) so after unloading cargo of woodchips, it would go back with empty wagons, but it also cost money and time, so unless You have something to bring as cargo on return trip, You have to charge double cost of transport.........

Normaly, trains go with cargo both ways, so using cheaper fuel and cheaper locomotives would make lesser cost of such transportation, therefore in other cases it could be ecconomic, but still consider bulk of woodchips necesary to raise heat enough to produce good steam, specially >>dry<< steam required in case of Tesla turbine... Even locomotives using coal neded to have reserve in size of one vagon of coal, specially if it was lignite coal, and for woodchips there would be need for 3-5 times greater volume to produce same caloric output......... Other solution is refueling at every station, just like old locomotives had to take water that was spent for using steam. But those old monsters were throwing steam on all sides, so no wonder they neded lot of water.

I still dont get what You need water treatment chemicals for? I would simply use destiled water, if water stone is problem, and without leaks of steam, there would be no need for replenishing it in closed system.......

Last of all, to condense steam it would be enough to have expansion chamber that would work same as in refrigerator, just here it would lower temperature of steam enough for it to condense, or at least I think so :-))

There would however be severall benefits that would lower price of locomotive if Biogas is used as fuel, as You can use same reservoir for gas that were used for diesel, there is no need for fuel pump, no need for big storage like in woodchips case and automatic feeder system, fireplace and steam generator, water and its treatment chemicals, while the rest remain same as if You use steam, if high rotational speed really cause problem and that have to be regulated by speciall gearbox as somebody mentioned.

Therefore, system using gas would be cheaper to produce and cheaper in use, and Tesla engines would provide raise in fuel efficiency use by themself.

Biogas produced would have lot of fringe benefits as I wrote before, therefore it is the way that is most economicall and bring most benefits, and that should be criteria for evaluating any project involving energy production and use.

So, dont say You are not ready for use of gas, because technology is available allready and Tesla Engines could use it as well, so there is nothing new to invent :-))

As I understand it, your wood chips are either free, or very low cost. This makes generation of "water gas" to fire your boiler worthwhile.

Although perhaps some reduction in efficiency, a 2 stage combustion can give benefits in reduced maintenance of your boiler.

Stage one produces water gas (the water in the chips should do this for you if they are burnt with restricted air flow). Stage 2 is your actual boiler where the water gas is burnt to raise steam. The advantage is that the section with the steam tubes (ie the high pressure section) has clean fuel, while the "dirty part of the process (and the high maintenance part) is separate and has no high pressure components to it.

Of course physically they are basically the one boiler, just a little mod to the combustion chamber required.

The approx amount of water needed can be calculated easily from the reaction equation:

C + H2O = CO + H2.

Knowing the carbon content of your chips, the required dryness is easily calculated. It won't be exact, but it gives a good start.

Depending on your chips, you may need to partly predry them, but diverting exhaust into a predryer could accomplish this.

Sounds like a fun project. May even eventually bring back steam as a viable locomotive power plant.

There could be a good future for what you develop here as solid fuels are cheaper and more readily available than liquids.

Keep us posted on your results.

That's the idea. Last time I checked, market price of wood chips was equivalent in BTU cost to diesel at $1.65 per gallon. In a lot of areas, wood chips are a waste product that requires disposal.

Porta developed the Gas Producing Combustion System for coal, but it adapts well to any combustible: http://www.trainweb.org/tusp/firebox.html

The locomotive will have an economizer (air preheater) so the hot combustion air will help. If the chips are stored properly they will dry to a certain extent- regulating the moisture content of the chips will be an issue for the customers buying them as well. Drying the chips a few percent shouldn't be a major technical challenge.

Better watch out for this >>few percentages<< as one project allready flopped on this: fresh chips have 60% moisture that has to be taken down to at most 30% to be able to burn...... That means You have to extract at least 50% of water (relative), or 30% absolute, but whichever way it is 300 liters per ton, and even with high enough temperature it take time for water to get out.....

Sorry to say, but my finances went so low that I would not be able to pay my IP, so for a week or two I would have to abstain from writting more posts........

Regards,

Marijan Pollak

I'm not an engineer, haven't gone to school for any of this stuff except for manufacturing in college, but this is my take on it. for the discs, the higher the mass the more likely to fail. with friction or speed comes heat, and when metal heats, the molecules tend to stretch and become brittle, causing stress fractures and breakage. probably the best medium for the disks would be a titanium alloy or carbon fiber. you can do your own research, but i think that titanium has been tested and been successful at temps from 15 kelvin to probably around 295-305 kelvin (which is about 139,650 degrees Fahrenheit). but titanium alloy only has an ultimate strength of 900 MPa (pascals) where as carbon fiber has ultimate strength of 5,650 MPa. carbon fibers' density is only 1.74 g/cm3 where titanium alloy has a density of 4.51 g/cm3. carbon fiber will be better, but more brittle. as to the second question, i believe that acceleration would stiffen the disc, but that might be a bad thing with a carbon fiber disc. you would have to do some actual stress testing (running two turbines with two different discs and maxing out the RPMs for both) and seeing which one failed first at high stress. oftentimes what works on paper won't work in the field.

just keep in mind i'm not an engineer, and i have no degree so this all might sound pretty stupid. let me know if it was helpful or not.

Not bad for a non- engineer

Heat is a major factor, very few metals get stronger as they get warmer. Operating temps can change your selection.

Some Graphine sheets made into disks (if you could get them thick enough) and coated with something to keep the oxygen from effecting the carbon at working temps would do a great job.

Destructive testing at Tesla turbine speeds can be spectacular so take all precautions.

Brad

Cool, we're back to the original topic!

Since this is a steam turbine and not a gas turbine I'm working on, I think that ordinary metals such as stainless steel will be strong enough (although creep is the problem and not strength.)

My original question was whether or not reducing the thickness of a disc of a given diameter (and hence its rotational mass) would reduce the forces on it. I think that's basically a wash, as reducing the thickness reduces the strength of the disc as well as the weight.

As far as destructive testing, that is another reason to keep the discs as thin as possible. In the event of a catastrophic failure, the pieces of a thinner disc will be less dangerous projectiles, hopefully not penetrating the turbine case. And don't worry- I don't plan on kissing the turbine when it's being spun up to 125% of rated RPMs

My only concern about a thin disc is having it develop "wobbles" around it. The proximity of the adjacent disc so close to it should damp this out and a number of thin discs spaced within the boundary layer thickness apart should amount to a set of discs which can be straightened by centrifugal force, yet prevented from developing "overtone" type perturbations within the individual discs by the boundary layers and proximity of the other discs.

It would be an interesting experiment to see if this actually works. Set up a few (carefully balanced) discs at the appropriate spacing, spin at high speed and see if they remain stable.

I think it will work but am not sure.

Good luck

Good post, but

probably the best medium for the disks would be a titanium alloy or carbon fiber.

The carbon fiber would only have strength in one axis, and when compensated with laminates with the stresses envolved delamination may occur, its a case of compromise

phoenix911

HAVE YOU THOUGHT ABOUT USING CARDBOARD?

chuckles

if you built one with cardboard, it would be neither expensive or dangerous. they did build a tesla blower out of the same....

It would take a bit of work but you can combine materials and designs to get the optimum properties. Even internal disk cooling is possible while remaining thin.

What you don't have is the luxury of being able to make lots of mistakes and try endless designs to perfect your turbine from the start.

It is simpler and faster to stick to original Tesla's design for start, and experiment later. Surely modern materials are already far better then those available in his time, 100 years ago? To start changing specifications before one replicate original invention is fastest way to failure, and then of course such person would say that such invention does not work.

You should not be concerned about heating of plates, because heat is just one form of energy, and according to law of Entropy, energy cannot go from cooler to hotter area but opposite. Therefore, temperature of plates cannot be greater than that of medium used. Take that into account to prevent buckling of plates, which was only problem Tesla encountered.

To find solution to plate heating problems, some thermal simulation should be done and perhaps some changes made in design. I would say that if surface of plates would be uniformly deformed to look like golf ball surface, or if there would be some radial ridges and/or shallow grooves on those plates, then buckling would be prevented and perhaps also some more torque extracted from working media. Of course, plates should be identical and mounted so that there is always same distance between surfaces everywhere.

On the other hand, that may disrupt proper spiraling of media over the plates, which is basic principle on which Tesla turbine works. So, simplest way is to make plates thicker, and increase their number. Most important is to keep distance of plates as Tesla specified, and instead of having thin plates we have to make edge of plates razor sharp, or nearly so........

I also think that it was plate buckling problem that kept radius of those plates smaller then they could be, as with greater radius there need to be applied lesser force on plate rims to produce same torque, just there should be greater volume of working media. So I believe that if wind is working media powering Tesla turbine, there should be no problems with plate buckling and greater diameter of plates could be used safely....

Yes, one more thing: if I remembered correctly, somebody suggested that for better efficiency 3 blowers at 120 degrees apart should be used, and this is not good at all because then there are three spirals of working media going down the plates on much shorter path, so neither of them would allow extraction of all possible energy from working media, so there would be less efficient work done. Working media should be directed at plate edges almost tangentially, so best effect should be produced if there is gap in front of blower paralel to plate rims between housing of turbine and turbine itself, and this gap has to get narrowed going around turbine, to become nearly zero when getting back to blower or working media entrance. This way working media would get compressed and therefore fastened, which would enhance energy extraction. Similar thing is practiced on some water turbines for same reason, but then there could be several outlets for water to hit turbine, because energy is extracted on one turbine blade and used water is removed at once so blade is free for next quantity of water to hit it.........

That are just some suggestions describing how I see it, but I am not mechanical Engineer nor material technology expert, so don't get mad on me if I wrote something stupid.... :-))

Thanks for all the great feedback, everybody.

Right now I have settled on smooth steel discs (easy to manufacture- just stamp or use a CADD laser/plasma/water jet cutter). They will be braced at the rim and hub -by bolts with spacer washers the correct thickness. This should prevent the discs from warping. The smooth washers should also (as Tesla found) increase starting torque without decreasing overall efficency. Will use the Aerospike nozzle also. The large exhaust area should help efficiency also, and if it exhausts into a condenser that will reduce the back pressure further.

Going to build a plastic version with dead CDs as a proof-of-concept model- I can reuse a lot of the parts on the steel version later. Again, will instrument the unit to determine horsepower output relative to the power available in the incoming compressed air.

When we scale up to the steam version, what do you think of supplying a small volume of steam to the nozzle at supercritical pressure and temperature? It would phase change to gas as it exited the nozzle with huge expansion, and the long path of the rotor would allow it to give up most of its energy.

That's good, Mark!

Only problem I see is energy expenditure while creating that superheated steam, since I believe that I have read somewhere how one need to spend more and more energy to raise temperature one degree higher as actual temperature rises. But perhaps I got it wrong, or I am not remembering it correctly, so I am ready to stand corrected.

While nozzle system would help reduce such high temperature, it would heat casing and turbine, so perhaps there would be need to use materials that would function normally at such temperatures or casing should be thermaly isolated from inside using newest techniques of depositing nano layers of different materials that together make superisolators. I also believe that at high temperatures steam can be more corosive than normal, and some mentioned possible cavitation problem.

I also did not get what those >>washers<< are or how they look like, due to my poor English knowledge, but perhaps I can Google this :-))

Wish You all luck!

The washers (spacers) are dount/torus/Cheerio shaped- discs with a hole in the middle. I am going to drill holes through all the discs in the rotor, around the outer edge and interior hole, and install bolts/screws through them. The spacers will be the same thickness as the desired interdisc spacing. So they will be assembled on the bolts as disc-spacer-disc-spacer-etc.

This will make the discs into a single assembly, with no center axle needed.

Will try to get a sketch posted on here tonight.

Mark, in a word: DON'T!

Maybe there would be no harm in having three of them, but still IMHO it is better to do without them. Whenever one would come in front of nozzle, fluid stream would hit and rebound, and I think You would have sound You would not like to hear. Also, did You say You intend to use discarded CDs? That cannot stand heat, much less superheated steam, so how would You test it?

If I would be in Your place, I would just use 1mm thick plates, which is more than twice required distance. That should make them rigid enough. If You find some scrapped computer HDs and could find severall of same model, that would be perfect since they rotate even 10 000 Rpm without buckling. Only downside is that there is feromagnetic layer on them, so they are good for experiments only. But then, they are 3" today and so You better find at least QUANTUM Bigfoot seria or something still older from 80's.....

As I wrote, Tesla have maybe put those washers in attempt to prevent buckling of plates, which You most probably would not need to do, using Duraluminium or Siluminium (sory if I have written this incorectly, I dont know English names for these Aluminium alloys. First is used in Airoplanes and second in marine Boats, as last contain Silicium so this alloy is corosion resistant.) or just Stainless Steel would do.

I also wrote it is first and last mistake many has made, to change originall engineering plan from step 1. So, copy original turbine as close as You can, and only when You see that it works as efficiently as Tesla claimed, then You would know that it is what You need. Leave experiments for later, and only if what You get from original seems to be amenable to ad hock improvements. What aint broken, need no fixing, right?

Would You not be happy enough to get 95% efficiency at half pound per Hp as You wrote at the beginning?

So if You get it, and there would be no buckling of plates in test runs, do it Tesla way and leave experiments for free time when Your production would be in full swing!

Remember, this turbine work so that spiral path is formed on those plates and anything in a fluid path would be obstacle that could render it non functioning or at least less efficient.

I repeat what I strongly believe, and that due to modern alloys there would be no buckling. I saw picture of one Tesla water turbine that still exist in his birthplace, Smiljan in Gorski Kotar, and it has had 1-3 cm thick plates (I cannot say how thick as there were no reference for comparison), so surely 1-2 mm would not be problem and plates surely cannot buckle. But then, You know how high temperature You intend to apply to that steam........

I was corresponding with somebody fro Kenya, claiming he and son has built 260 Hp, 60 Kg Tesla engine, and I would look in my correspondence so You can contact this man, assuming this was real story, of course...... Would something like this fit Your plans?

Wish You all the best!

Marijan Pollak from Croatia

I plan to use discarded CDs spun by compressed air for a small-scale test model. This I can work on with the equipment I have available right now.

If I use a regulator to supply a fixed pressure and volume of compressed air, and a de Prony brake to measure turbine output, I can easily evaluate changes in the design. I will change one paramater at a time, and log the results.

I am going to test it initially without the spacers at the disc edge. Then I will add the spacers to see how this affects torque. Yes, I expect there to be some cavitation noise at high loads. The spacers being round, the fluid stream should creat high pressure in front of them and low pressure behind, but maintain a mostly laminar flow around them. Comments?

Once I settle on the nozzle and rotor designs, then I can scale it up for a full scale steam operated prototype. Yes, the design will have to be re-optimized for steam vs compressed air (different inter-disc spacing and nozzle size, etc.)

I plan to use mild steel for the prototype, to reduce costs. Once I start long-term tests, then it will be time to move up to quality materials.

Also on the drawing board is a gas (combustion) turbine using two boundary layer disc units on the same shaft, one as the compressor and the other as the turbine. This critter will require seriously robust metals in the compressor, such as 2000 series aluminum alloy (the current US designation for Duralumin.)

Dear Mark, formaly Your tactic seems fine, but I have to stress some points You perhaps overlooked.

1st. Tesla turbine use Adhesive force to work. With different materials and different fluids You get different results. You would be unable to use results of one system as yardstick of another.

2nd. If You dont stick to original blueprints and recreate originall results, how would You know where thing went wrong with different materials and fluid combinations. Therefore You would waste time on experimenting, and when You adjust parameters to one combination, it would most likely be wrong with another.

3rd. Once You mention that just by adding plates You can get greater power density. Since holes for fluid removal have to have greater capacity than total volume of entering fluid for reasons described before in my posts, if You add plates then holes should be enlarged to be able to conduct slowed down fluid out of turbine else that fluid would clog turbine, so result would be less efficient turbine. Same thing may not happen if diameter of plates is enlarged and volume of fluid is not changed. In such case perhaps speed of fluid can be greater as it would be extracted more efficiently.

I again repeat that I am not >>real<< Engineer, but more >>theoreticall<< Engineer or >>Meta Level<< Engineer since I am Systems Engineer.

It is also true that theory and practice sometimes are not really compatible, but while some theories still cannot be made practical due to state of technology, in practice whatever is working have some theory behind it.

Theory may come later as explanation of practice, also, so it is valid only for practical results it want to explain.

But Theory of Systems seek to explain systems in generall, and was so far proven sound.

>>There is no effect without cause<< is its stronges rule/Law.

You can meddle with parameters and 99% of time get wrong results if You dont know cause of effects.

In case of Tesla turbine there is no theory, or maybe theory of Laminar Flow can be applied even if they perhaps did not consider spiral Laminar flows, but here it is not >>spiritus movens<< of system but adhesive force.

Therefore, I conclude that gap between plates is same for all fluids and should not be changed.

Materiall used should have maximall adhesive force with fluid used, and I would say nobody has studied that, so You would lack data to apply or at least to be able to make >>educated guess<<.

That is one more reason to stick as closely to originall plans that Tesla made as possible.

In the end, if You intend to use discarded CDs, which I believe some have done allready and there are pages showing results on WEB, You better see what happened to that experiments first, or since this discussion went on for months, You could have tried to do it allready instead of discusing this and that. Materials are cheap so it would cost You only some work time and efforts, and if You intend to have same diameter plates later then You would be able to reuse parts with metal plates, but I expect that with change of materiall results would change also.

It may be case that CDs are not having adhesive force strong enough, or because of great air speed there is no time for it to react with fluid used (i think others used water from pipe falling verticaly on edge of CDs, which is also not correct way to extract its energy, but still they got some results), but if casing is made like I described before, then system would work with any air speed. How efficiently, that depend on Adhesive force binding fluid and plates together.........

So, why did You not have done it allready?

As I see greatest problem would be to make casing for turbine, as it cannot really be expanded if necesary for greater diameter of plates.

How You intend to do it? What tools/materials You have at disposal? CNC cutter?

That would be great to have, and I could see at once how I would make casing out of profiles held together with several long screws. If You leave enough material on sides, perhaps You can recut inside to accomodate greater diameter of plates later.

I wish I have such possibilities You have to freely build whatever You can imagine!

Anyhow, go for it!

Still, exactly because it would be small difference in cost for You, in Your place I would recreate originall turbine first.......

Sorry for spelling errors, CR4 Speling Checker again have thrown some error at me...

Regards, Marijan Pollak