Repurposing Industrial Scrap

[healerenergy]

I recently brought home a massive motor and flywheel and am going to set it up as just a flywheel for my combined energy project. This is just the beginning of a big project.

I am going to start with some of the math.

I am pretty good at some math but would like help making sure I get things right with this project

So far I found some pretty good math on line but have never used this exact kind of math before.  The math I found is this

Physics:

        Stored energy = sum of kinetic energy of individual mass elements that comprise the flywheel

        Kinetic Energy = 1/2*I*w2 , where

        I = moment of inertia (ability of an obeject to resist changes in its rotational velocity)

        w = rotational velocity (rpm)

        I = k*M*R2  (M=mass; R=radius); k = inertial constant (depends on shape)

Inertial constants for different shapes:

        Wheel loaded at rim (bike tire); k = 1

        solid disk of uniform thickness; k = 1/2

        solid sphere; k = 2/5

        spherical shell; k = 2/3

        thin rectangular rod; k = 1/2

I need to do this for both the rotor and the flywheel so I can find out how much horse power I will have to have to get it moving and up to speed.

The flywheel weighs 6920 pounds.

The rotor now weighs 6120 pounds.

The shaft weighs 3580 pounds.

George

[wdyasq]

Yes, your formulas are correct. I would convert the 'pounds' to kilograms or Newtons so you will get your answer in Joules, which are "Watt/seconds". Remember that power is a function of time.

I wish I knew of a good Physics website to get you up to speed. Remember as you calculate this that if the flywheel fractures, all of the energy is quickly absorbed by the surrounding or nearby structure. One does not want to be part of that structure.

Ron

[healerenergy]

The compressor that this motor and flywheel used to belong to ran at 350 rpm and I am considering possibly taking it to 500 rpm but no more than that.  I think your idea of changing from pounds to kilograms is a good thing.  So the

flywheel is 3 138.859 200 4 kilogram

rotor is 2 775.985 304 4 kilogram

shaft is 1 623.860 684 6 kilogram

George

[healerenergy]

I found this site on one of my google searches.

http://flywheel.esmartbiz.com/basics.htm

George

[Capt Slog]

I wish I knew of a good Physics website to get you up to speed.

This is really good...

http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html

It takes a little navigating at first, but once you're into it, it's very helpful.

 .

[BigBreaker]

I think you mean watt x seconds

[BigBreaker]

You will find yourself with enormous power potential in that flywheel, but less energy than you would guess.  It would be great for welding, motor starts and other short term high power needs.  As a battery it'll be terrible.  Only the high tech, high RPM flywheels achieve decent energy density.  You also need to contend with frictional losses - the high tech flywheels use air or magnetic bearings.

Think about it this way, 500 RPM is ~8 RPS.  The effective diameter of the flywheel is? 2 meters?  So the circumference is about 6 meters.  8 RPS and one rev = 6 meters, so ~5000 Kg at 50 m/s.  Kinetic energy is .5 x mass x speed^2, so .5 x 5000 x 50 x 50 = 6,250,000 joules or 1.7kWh.  A 12v battery bank of similiar capacity would have 140 Amp hours.

One thing about flywheels... double the RPM, quadruple the energy storage.  That's why the big boys spin their composite wheels at 30k+ RPM.  If you spin that wheel up to 2000 rpm, you'll have 20+ kWhs to work with.  Lock'r down tight!

[healerenergy]

I really thank you for your input and I will try to have all the measurements in a day or so, so we can do this right. I haven't measured the diameter of the flywheel yet but I think it is nearer 8 feet than 6 feet.  

Rotor ID is 145.5 cm

Rotor OD is 162.5 cm

Rotor height 162.5 cm  

George

[hiker]

sence you have such a hugh flywheel this might be a good read--just one out of many on google search...

                http://www.rustyiron.com/engines/flywheel/

[healerenergy]

Thanks for the site it is a good piece of information.  My main intent is to even out the energy between my VAWT and generator or alternator.  So I don't think I will be spinning this up to real high speeds.

[healerenergy]

As promised the flywheel specs follow.

Flywheel ID 212 cm

Flywheel OD 256 cm

Flywheel height 256 cm

George

[healerenergy]

I thought it was time to show everyone all the pieces of the motor less bearings so here goes.

Stator

Rotor halves

Shaft with counterweights

Flywheel halves

George

[BigBreaker]

My approximations are still going to be pretty close.  The real variable is the speed you run the flywheel, not the diameter.