turbine

[MTC]

I must say I have read a couple of the topics and I am very impressed by the knowledge of the people on this site.

WE (my company) have been developing a new type of turbine over the last 5 years or so. It is not a Tesla turbine but is a boundary layer turbine. I do not want to divulge exactly how the turbine works for obvious reasons. But I can talk about how it has preformed to this point and our plans if that is of any interest to anyone. Our next step is going to be to conect a pulse jet to the the turbine, this is why I am posting on this site.

The points of interest of this particular turbine are: the turbine has no problem with condensing gases; the turbine is relatively inexpensive to build.

This is a very part time endeavor so if I mention years, that is not full time work on the project. We have tested a couple of proto types on steam and water. So, no problem with water condensing because the same turbine ran both on steam and water. To do this testing I made a small boiler out of a propane bottle (not recommended for others) I put hot water heating elements in the side bottom of the tank and a pressure relieve valve. This gives a run time of a few minutes in which we conducted tests, rpm, torque, temperature, etc.

Testing torque was not easy; I had to create a device, using a car brake rotor and some bicycle brakes on a pivot arm. This did give us some sustained torque. (1.5 foot pounds at 1250 rpm) Not much for power, and I have to admit that I did not run the boiler power calculation until after I was into testing and the numbers were not that good. I simply ran in as much power as the 100 amp system could handle, thinking this will be a good bench mark. Ends up I only had about 2 boiler HP and about 5 minutes of run time. Not earth shaking by any means; however I set the turbine up for closer to 50 hp. so this was not a good test of the turbine for efficiency. There was one really good thing that happened though. We sent in 150 psig steam at about 350 F and discharged 180 F water vapor. Most engineers will tell you that there must have been a huge vacuum to achieve that. I believe that the turbine does create a vacuum but not to the degree that would be required to create 180 F steam. Anyway; a boiler big enough to produce the power I needed was not cost effective.

The next endeavor is the gas fed turbine and the pulse jet seemed a very good way to start. I have a friend with a gas well on his property and we would like to exploit it for power. He has been testing the well, and we are not sure at this point how big a generator we can put on there yet. The plan is to test a small turbine and jet then put more money into the larger system once we have the data.

I am at work now and can not post any pictures but will try later.

Thoughts?

[racketmotorman]

Hi MTC

Sounds like your 180F TOT was caused by the limited amount of steam trying to heat the turbine wheel up , steam at 150 psig can produce velocities of ~3,000 ft/sec , for you to only be running the turbine at 1250 rpm either means a lot of gearing or a lot of wasted energy from the turbine .

I should mention I've operated steam boilers of up to 60,000 lbs/hour and been playing with gas turbines for coming up to 20 years , I'd need more info before commenting further .

If you want to generate electrical energy efficiently and cheaply , feed your fuel into an IC engine and keep clear of pulse jets to power your turbine .

Cheers
John

[MTC]

The RPM ratio to gas velocity is not a direct correlation as it would be with conventional turbines. I have no way of telling what the velocity of the steam exiting the nozzle is; but it was not an Alfa Lava nozzle so I highly doubt that the velocities were that high.

The idea of using the pulse jet is two fold. One: it is inexpensive to purchase. Two: it will give us the data needed to build larger more efficient systems.

I can not say if we will be using a pulse jet down the road, but I am very much looking foreword to the results of this turbine.

If I had access to a larger high pressure boil I would still be working with steam.

Thanks for the comment.

[racketmotorman]

Hi MTC

When I fitted a turbine wheel to a pulse jet http://www.youtube.com/watch?v=uqMn0A2aUdo I was rather disappointed by the results , the fuel burn rate was horrendous for the power produced ...............I get much better results with my gas turbine gas producers driving freepower turbines .

Cheers
John

[MTC]

I watched the vid, very interesting! (except the crack of course)

As for the burn efficiency I had thought of staging turbines; burning the gases after one turbine fed into a pulse jet running another turbine. Is after burning an option? My main point is that I really have enough to worry about with my own turbine and do not wish to invent new jet engines to solve my problems. In short I really hope to use inexpensive off the shelve components to run my turbine. This may not be possible on either point, but we will never know until we try.

[racketmotorman]

Hi MTC

Without knowing more about your particular turbine its impossible to give any indications as to how/if afterburning/interburning would be effective or possible.

Turbines need to be run at fairly high speeds to efficiently convert dynamic gas energy into shaft energy , my bike engine http://www.racketmotorman.turbinebuilde ... hp?album=3 and kart engine http://www.racketmotorman.turbinebuilde ... hp?album=4 even though only powered with a low pressure ratio turbo based gas turbine required in the case of the bike a power turbine capable of spinning >30,000 rpm to extract the shaft horsepower .

At present I can't understand what you are attempting , fuel efficiency requires pressure ratios to be fairly high otherwise the thermodynamics simply won't allow good thermal efficiency no matter how many times you try afterburning between turbine wheels , all you'll produce is a lot of very hot gases doing nothing

Have you thought of running your turbine off an automotive exhaust ?? ............compound engine style

More info please

Cheers
John

[MTC]

Yes, I have thought of running off exhaust gas of an engine. It was my very first thought on the matter. The problem, I am guesing is that most engines can only handle a back pressure of about 5 psi. I really do not need pressure I need momentum, or the combination of velocity and mass to do work in my turbine. So what sort of velocity can you get straight out of an internal cumbustion engine?

I will have a small combustion turbine ready for testing in about a month an could test it with any number of different sources.

What I am really doing or trying to is fully test my turbine on combustion gasses. I reallize that without seeing the turbine it is hard to understand the differences between this turbine and other conventional turbines. It can create usable torque a lower rpms. One prototypical test using a 4" turbine with 150 pisg steam, the turbine attached to a 90 amp 12 volt alternator fulley loaded. The turbine and alternator at a stand still, opened the steam valve and the turbine ran up to 9000 rpm bring the alternato up to 2250 rpm's is 3 seconds (4 to 1 ratio in pulleys). So my turbine or I should say my company's turbine can produce torque a very low rpm's even zero. This test could not be sustained more then 20 seconds when the boiler pressure would drop below 50 psig, this was below the pressure to operate the turbine.

Anyway this is a very interesting dialog and I am enjoying it. Sorry I can not explain more, I just do not need a bunch out there running before I have sold one. I hope you understand.

[racketmotorman]

Hi MTC

Yep , I understand confidential information

All gas turbine freepower turbine wheels can create maximum torque at nil rpm , generally ~ twice max rpm torque , the maximum total pressure that my bikes freepower turbine experiences is ~12psit , this is a mix of several psi of static pressure and the rest dynamic pressure inherent in the high velocity gases, the bike produced 115 rear wheel horsepower , so lets say 120shp at the turbine wheel whilst running ~33,000 rpm with a mass flow of ~1.8 lbs/sec , 120hp at 33,000 rpm represents ~19 ft/lbs of torque at the turbine wheel , this would have been roughly doubled at nil freepower rpm with the gas producer at full power , so lets say 38 ft/lbs at the turb shaft , multiply that by the bikes overall gearing of 18.56:1 and we have ~700 ft lbs of torque at the rear wheel to accelerate some 830 lbs of bike and rider http://www.youtube.com/watch?v=P-5PgWqgIJo

Most turbocharged auto engines run exhaust manifold pressure up to around twice the inlet manifold pressure during hard acceleration.

You have to do your turbine calculations using total pressures and temperatures in absolute terms , so your turbine inlet pressure will be a combination of static and dynamic forces .

If you're keen on using steam turbines , may I suggest you get a copy of this book .........ISBN 1 85761 075 X Tee Publishing in the UK, book is called Model Steam Turbines by H H Harrison , just a small book of ~60 pages but very enlightening

Cheers
John

[MTC]

John,
The steam market seems to be a much harder market to crack. I believe that a 100% condensing steam turbine has a place in the market but may be a hard sell initially. The the lack of easily available testing equipment (50 hp high pressure boiler or larger) make the task of verifing the steam aspects very hard.

Cumbustion energy is by far easier to come by and with my friend having a gas well, it is any easy next step.

I have run the 4 inch turbine at 33000 rpm however that was a max rpm and could no longer produce power at that speed, a loaded rpm may have been somewhere between 10 and 20,000 rpm. I can tell you that larger usuable turbines will never have loaded rpms above 10,000 and more likely be around 5000. This should make things a lot easier because we can us conventional gearboxes and transmisions.

I am not familar with the free power turbines?

Thanks

[racketmotorman]

Hi MTC

What you are playing with is a freepower turbine , its free to rotate independently of the gas producer rotor , the Allison 250 helicopter engine has 2 freepower turbines producing the ~400 shaft horsepower , the larger is 212mm -8.5" in dia and both rotate at 33,000 .

To have a "slowly" rotating turbine it'll need to be rather large in diameter , several feet , or you need multi staging with several stages so as to have limited pressure drop across each stage with limited gas/steam velocities

Cheers
John

[MTC]

John,
I would like to look at the video, but I am at may day job (night job) and it is not permited. I will check it out on the morrow.

Thanks much for you insight.