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Author Topic: Who here has great knowledge about fluid driven turbines?  (Read 4826 times)

Offline kornbredrsqar

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I have designed and built an air driven turbine with a rotor that is 4" in diameter, is about 2" in length, turns at just over 12000 RPM, and only consumes 4-5 cfm of compressed air @ 170 PSI. I have been told by few people that my design "in there opinion" is not more efficient than other turbines on the market, but the closest motors that I can find to compair it to consume between 40 to 170 cfm, and there is room for substantial improvement in my prototype as it is built from scavenged parts and scrap metal that are not precisely machined to fit as intended, based on the figures above can anyone calculate any sort of efficiency rating or do I need more data?


 

Offline Geezer

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Who here has great knowledge about fluid driven turbines?
« Reply #1 on: 26/04/2011 02:10:33 »
I think Peppercorn is your best hope.

I think he'll need a bit more information though. Speed and air consumption does not tell you much unless you also know the torque that was being produced.

« Last Edit: 26/04/2011 04:50:20 by Geezer »
 

Offline kornbredrsqar

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Who here has great knowledge about fluid driven turbines?
« Reply #2 on: 26/04/2011 15:18:22 »
That's what I was afraid you would say, is there any simple way to measure torque besides hooking up to a dyno system?
 

Offline SeanB

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Who here has great knowledge about fluid driven turbines?
« Reply #3 on: 26/04/2011 16:48:35 »
Connect to a generator ( or an induction motor run as one) and measure the power developed into a resistive load ( or the current and voltage across a light bulb load) and you will have an idea as to what power you are getting. If you have a small unit a DC motor makes a fairly good generator when used in reverse. A motor from a scrapped printer is probably the easiest to find, and is reasonably efficient, and you just have to use a 12V 5W automobile lamp as a load for a beginning.
 

Offline Geezer

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Who here has great knowledge about fluid driven turbines?
« Reply #4 on: 26/04/2011 18:04:24 »
I agree with Sean. A DC motor running as a generator will give you a reasonable estimate of the power. It won't be 100% efficient, but the efficiency should be quite high. I would guess somewhere between 80% and 90% ??
 

Offline kornbredrsqar

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Who here has great knowledge about fluid driven turbines?
« Reply #5 on: 26/04/2011 23:45:01 »
thanks ,I spent most of the day looking on line and found several ideas that are simalar to this
I've got an alternator or two lying aroud and a power stearing pump as well, one idea was to use a pump to put a load on the motor and hook a scale to a torque arm coming off the motor ,the alternator sounds easiest, I guess I'll take a stab at that first.
 

Offline kornbredrsqar

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Who here has great knowledge about fluid driven turbines?
« Reply #6 on: 06/07/2011 00:25:15 »
Ok here's what I've come up with so far; using a set of fish scales and a piece of serpentine fan belt to act as a brake on the drum I fashioned from duct tape on the shaft ,I was able to get a reading of about 1.5 to 1.8 lbs. @ around 6000 rpm with air consumtion still around 5 cfm, not to impressive so I had a computer simulation ran and the max torque of 13.6 lbf-in was achieved at stall with 170 psi and 23 cfm the higher cfm was due to increasing the size and number of nozzles to get a maximum torque reading and solve some issues with air speed in the simulation ,more tweeking of the dimensions and nozzle configuration and maybe increasing the number of blades will be tried in future testing, when funds are available.
P.S. there's a short video of my motor on youtube titled new air turbine
 

Offline Geezer

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Who here has great knowledge about fluid driven turbines?
« Reply #7 on: 06/07/2011 00:58:59 »
Are you aware that when it's stalled it may be prodcing a lot of torque, but it's not producing any power?
 

Offline kornbredrsqar

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Who here has great knowledge about fluid driven turbines?
« Reply #8 on: 11/07/2011 23:06:58 »
YES!
 

Offline kornbredrsqar

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Who here has great knowledge about fluid driven turbines?
« Reply #9 on: 11/07/2011 23:22:48 »
Acording to the man that ran the simulation, he had to run it in a stalled possission because the turbine would spin up to infinity and the whole program would shut down. I am not sure why they were not able to put in a variable amount of resistance and come up with a power curve over a given range of rpm. maybe when I give them more money they will figure that one out.
 

Offline Geezer

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Who here has great knowledge about fluid driven turbines?
« Reply #10 on: 12/07/2011 03:15:14 »
Acording to the man that ran the simulation, he had to run it in a stalled possission because the turbine would spin up to infinity and the whole program would shut down. I am not sure why they were not able to put in a variable amount of resistance and come up with a power curve over a given range of rpm. maybe when I give them more money they will figure that one out.

Er, I wouldn't give them any more money if I were you. Either the simulator is no good, or they don't know how to use it.
 

Offline peppercorn

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Who here has great knowledge about fluid driven turbines?
« Reply #11 on: 12/07/2011 23:23:42 »
My sixth-form (or 'seniors' for those State-side) engineering college had a electric dyno rig that we students used. Is there a place near you that might have something similar? A quiet word with the faculty (plus offer of liquid refreshment) might buy you some time on one.  - Not sure if they will have a nearby air-line though... ?

I think this type of setup is the only way you are going to get a meaningful plot for your device.  Having the unloaded and fully torqued (just above stall) are going to be a good indicator but a full curve is going to be more meaningful - esp. if you want to convince folks that you have something marketable down the line.
 

Offline Geezer

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Who here has great knowledge about fluid driven turbines?
« Reply #12 on: 13/07/2011 01:32:23 »
Not to be a spoilsport or anything, but there is not a lot of point in worrying too much about the efficiency of your air motor. The problem with air motors is the very large amount of energy lost while compressing the air.

It's so bad that there were (are?) government funded incentives to encourage industries to replace their air motors with electric motors.
 

Offline Atomic-S

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Who here has great knowledge about fluid driven turbines?
« Reply #13 on: 16/07/2011 05:45:48 »
Air motors do a few things that electric motors do not do easily.
 

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Who here has great knowledge about fluid driven turbines?
« Reply #13 on: 16/07/2011 05:45:48 »

 

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