Well, I have a pretty basic windmill ready for the SBS Earth Day Celebration! It's the HAWT, which doesn't yet turn. I could never find out where to get pillow block bearings, and I don't want to have it turning on a solid pole because that inhibits the wire. The only way I see to make it turn effectively is to have it rotate on a pipe, because that way the wire goes down the middle and won't get twisted up by the windmill turning. Plus, if the wire got twisted, the power of the wind may well rip the wire off the motor which would remove the load from the windmill letting the blades turn very fast. In other words, it will point in only one direction, but that is okay! Since it is equipped with an alternator, it will produce power no matter what way it turns.... this is a plus for right now since it is going to be static (if the wind comes from the back, it will turn backwards).
Hopefully Earth Day will be fun!
Thursday, May 1, 2008
Wednesday, April 30, 2008
Windmill almost complete!
I skipped school today... =D. I did however, get a lot more done than I would have at school! I modified the axle that I found in the printer to allow for a skateboard bearing to fit on, then attached the windmill blades on the end. I have to secure it onto the platform but that is just a matter of drilling some holes and stuff. Attaching the motor might be tricky ... I get to build a motor mount! woohoo
Monday, April 28, 2008
Rotating Tower: Solved
So I was talking with my dad about bearings and my tower issue with not being able to acquire pillow block bearings, etc. and he had the idea of using an old computer chair as the rotating part. The pillar is probably hollow which allows for the wires, the top can be adjusted to fit with the base of my current windmill easily enough, and the very bottom can be fastened to whatever tower or post is available. Sweet!
In other news, today I ripped open a printer and found three motors! One DC motor and two AC stepping motors. Ethan swiped the DC one, but I still have two AC motors which are both permanent magnet (I assume) and are fairly strong. One generates up to 15V with the electric drill, and the other generates 10V with the electric drill. I'm hoping to attach one or both of these to the windmill, though I'm not exactly sure how yet. It's probable that just the 15V will make it onto the scene, but it would be cool to have two motors up there!
In other news, today I ripped open a printer and found three motors! One DC motor and two AC stepping motors. Ethan swiped the DC one, but I still have two AC motors which are both permanent magnet (I assume) and are fairly strong. One generates up to 15V with the electric drill, and the other generates 10V with the electric drill. I'm hoping to attach one or both of these to the windmill, though I'm not exactly sure how yet. It's probable that just the 15V will make it onto the scene, but it would be cool to have two motors up there!
Friday, April 25, 2008
Images
First picture is of the tower joint between two 4 by 4's
Second picture is of the VAWT windmill from the side
Third picture is the VAWT from the top, so the blade profile is visible
Fourth picture is the HAWT windmill the broke the wind chime
Fifth picture is the swivel for the VAWT windmill that doesn't work
Sixth picture is some electronics: In my hand is the rectifier, the coil on top is from the dish washer, the coil on the bottom is from the fan (identical to the one currently on the HAWT windmill), the wood disk in the middle has some NIB magnets from various hard drives glued to it, and the rest of the stuff isn't too important.
Thursday, April 24, 2008
Tower Construction Etc.
Today I decided to give tower building a try. I had some old 4 by 4's lying around from the tennis court fence and thought a few of them would make a good tower. I screwed some boards around the joint to hold them together and so far I have a pretty long 4 by 4 sitting in the garage. The plan from here is to take a couple shortened 4 by 4's and create a joint for the tower to pivot up and down on. The two shortened ones will be cemented into the ground, and in between will be some sort of rod that the third long one (the one sitting in the garage) will pivot on. It will be something like a trebuchet where in one position it is vertical (after the trebuchet has been released and has gone limp) and the other position the highest point is on the ground (trebuchet loaded 'n' ready). This is hard to describe with words, there is an image of a similar one here, though it is made of metal instead of wood and the pivot is in the middle instead of to one side. Anyways hopefully something will be erected in my backyard in the near future...
In other news, the HAWT windmill that I had made was wedged in an apple tree today and spun so fast that it broke a nearby wind chime. I was amazed, since it couldn't even turn into the wind being wedged in an apple tree and all.
In other news, the HAWT windmill that I had made was wedged in an apple tree today and spun so fast that it broke a nearby wind chime. I was amazed, since it couldn't even turn into the wind being wedged in an apple tree and all.
VAWT Construction
So Ethan came over yesterday and we made a VAWT. It pretty much is awesome and we polluted the stream. The only problem is it doesn't work because the bearings we have (wooden dowel through drilled holes) kind of suck. I need to acquire pillow block bearings somehow, that way I'll be able to have good bearings and balance it correctly (it is a tower and when the balance is off, all the pressure is applied directly to the bearings).
Also someone on a forum directed me towards stepper motors as a source for magnets. Apparently printers and vending machines have them... so if Richard has some old printers....
Also someone on a forum directed me towards stepper motors as a source for magnets. Apparently printers and vending machines have them... so if Richard has some old printers....
Tuesday, April 22, 2008
Construction Time Again
Good album! In other news, I've been constructing the turbine itself! The first one is a HAWT with three blades. They are each flat boards attached to the main shaft at an angle so that when the wind hits them they turn from drag. I have also cut out pieces for a 'lift turbine' which uses an airfoil to get the tip speed much faster than the airspeed. This one will take a bit more work since I have to shape them just right.
The prop is mounted directly to a fan motor for now, which is taped to a board. It's very wobbly and wouldn't last ten minutes in any sort of "weather." The board that it is taped to will hopefully swivel on something eventually, provided I get some sort of bearings on it. For now the tail is rather useless, but it does have one.
I've got plans floating around in the back of my head to create a VAWT too. Might be about time to dust off the table saw...
The prop is mounted directly to a fan motor for now, which is taped to a board. It's very wobbly and wouldn't last ten minutes in any sort of "weather." The board that it is taped to will hopefully swivel on something eventually, provided I get some sort of bearings on it. For now the tail is rather useless, but it does have one.
I've got plans floating around in the back of my head to create a VAWT too. Might be about time to dust off the table saw...
Thursday, April 17, 2008
HAWT vs VAWT
HAWT - Horizontal-Axis Wind Turbine
VAWT - Vertical-Axis Wind Turbine
So here's the dilemma. A HAWT is way more efficient, but it generally requires elevation. VAWTs are much less efficient because half the time they are fighting the wind, but they have the ability to be down low to the ground. Since I'm renegade, I am going to opt with HAWT and build a tower somehow =D. Other groups seem to have opted for VAWT, at the beginning I didn't understand why, but I hadn't considered the height limit of 3m. With that limit, it's probably best to make a VAWT since the wind will be so irregular down low.
I've got two plans going simultaneously as a result: (both HAWT)
Plan A involves three thin flat boards of wood. The thin boards will be mounted on a circle of wood at an angle using triangular blocks of wood. This will make a drag windmill I assume, since the air hits the blades and makes them turn.
Plan B involves some online instructions here. I've scaled them down to 50% and then squashed that a bit to allow it to fit my scrap wood boards. So far I've got three blade cutouts, but no shaping has been done yet. I think I might have to go to my friend's house to use his band saw. These blades will be much better once finished, but they will take considerably more work to construct. The tips of these guys are going to be very thin, so I may end up coating them in fiberglass for strength even though epoxy is rather heavy.
I'm still unsure of the bearing setup. I will most likely end up using the armature from the fan that I stole from the dump. In this case, it might be smart to build a rotor the same exact size as the one that originally matched the fan motor. We'll see how the magnet collecting turns out... I may want to buy a bunch that are the same size to fit with the armature that I have.
VAWT - Vertical-Axis Wind Turbine
So here's the dilemma. A HAWT is way more efficient, but it generally requires elevation. VAWTs are much less efficient because half the time they are fighting the wind, but they have the ability to be down low to the ground. Since I'm renegade, I am going to opt with HAWT and build a tower somehow =D. Other groups seem to have opted for VAWT, at the beginning I didn't understand why, but I hadn't considered the height limit of 3m. With that limit, it's probably best to make a VAWT since the wind will be so irregular down low.
I've got two plans going simultaneously as a result: (both HAWT)
Plan A involves three thin flat boards of wood. The thin boards will be mounted on a circle of wood at an angle using triangular blocks of wood. This will make a drag windmill I assume, since the air hits the blades and makes them turn.
Plan B involves some online instructions here. I've scaled them down to 50% and then squashed that a bit to allow it to fit my scrap wood boards. So far I've got three blade cutouts, but no shaping has been done yet. I think I might have to go to my friend's house to use his band saw. These blades will be much better once finished, but they will take considerably more work to construct. The tips of these guys are going to be very thin, so I may end up coating them in fiberglass for strength even though epoxy is rather heavy.
I'm still unsure of the bearing setup. I will most likely end up using the armature from the fan that I stole from the dump. In this case, it might be smart to build a rotor the same exact size as the one that originally matched the fan motor. We'll see how the magnet collecting turns out... I may want to buy a bunch that are the same size to fit with the armature that I have.
Wednesday, April 16, 2008
The Needle Has Spoken!
Well, those fan motors turned out to be very inspiring! I ripped one apart and the insides were very simple. Stator with a few coils that were easy to see, plenty of steel laminates, and a rotor consisting of what looked like a bunch more steel laminates.
I removed the fan blades from the rotor and connected it to the power drill. This generated a little AC power! This was the first time the multimeter needle moved without me shaking it. I then took the magnets I had taped around the wooden block and re-organized them so that they fit inside the new stator setup. I spun these and noticed even more of a twitch in the multimeter needle! SWEET! (and that's with ten little ceramic magnets!)
The next step was hooking up the rectifier. That was only a matter of rewiring a few things since it's just a little rectangle with four terminals. When hooked up to the multimeter this time it produced DC power! It peaked at about .4V ... about a third the voltage of the dead AA battery I found. This is all very awesome! More to come...
I removed the fan blades from the rotor and connected it to the power drill. This generated a little AC power! This was the first time the multimeter needle moved without me shaking it. I then took the magnets I had taped around the wooden block and re-organized them so that they fit inside the new stator setup. I spun these and noticed even more of a twitch in the multimeter needle! SWEET! (and that's with ten little ceramic magnets!)
The next step was hooking up the rectifier. That was only a matter of rewiring a few things since it's just a little rectangle with four terminals. When hooked up to the multimeter this time it produced DC power! It peaked at about .4V ... about a third the voltage of the dead AA battery I found. This is all very awesome! More to come...
Free Stuff
So I went to the dump today and stole a few motors. I took this big double fan thing and then I ripped the stator off an old washing machine. Mary thought I was trying to steal stuff and sell the metal for profit but I told her I was making a windmill and she let me have it. I'm not sure she believed me though! Anyhow perhaps I'll get some pics up here soon. I'm not sure about the double fan, but the motor in the washing machine had an electromagnet for a rotor. I couldn't get the rotor out anyways because it was attached to something on the other side of some sheet metal. It had a few real nice bearings that were very tempting, but I had limited tools and not so much time. I have yet to crack open the fan motors, but since they are AC I'm going to bet they have electromagnet rotors.
If I didn't mention before, the rotor has to have a magnetic field provided by either permanent magnets or electromagnets. An electromagnet is a coil of wire with a charge in it... which isn't good for a windmill. It's possible to use electromagnets in windmill rotors, but it's much more complicated and the fact that the rotor has to be charged for the electromagnet to work detracts from the overall power output of the turbine. The alternative, namely permanent magnets, is great, but expensive. That is the reason why most AC motors don't have permanent magnets, it just isn't cost effective. (for instance, the magnets might cost $100 whereas the electromagnet/coil might cost $5-$10)
A new term:
Steel laminates are those layers of steel in the stator/rotor that help with overheating. The spinning creates eddy currents and the steel laminates help to dissipate those. Hopefully I'll get some picture up here soon, the stator I ripped from the washing machine is really cool.
If I didn't mention before, the rotor has to have a magnetic field provided by either permanent magnets or electromagnets. An electromagnet is a coil of wire with a charge in it... which isn't good for a windmill. It's possible to use electromagnets in windmill rotors, but it's much more complicated and the fact that the rotor has to be charged for the electromagnet to work detracts from the overall power output of the turbine. The alternative, namely permanent magnets, is great, but expensive. That is the reason why most AC motors don't have permanent magnets, it just isn't cost effective. (for instance, the magnets might cost $100 whereas the electromagnet/coil might cost $5-$10)
A new term:
Steel laminates are those layers of steel in the stator/rotor that help with overheating. The spinning creates eddy currents and the steel laminates help to dissipate those. Hopefully I'll get some picture up here soon, the stator I ripped from the washing machine is really cool.
Construction Begins
I paid a visit to RadioShack yesterday. There are not many truly useful things there. I was able to pick up a rectifier, and some magnets, but the magnets are little 1" by 3/4" ceramic ones and probably won't do much.
I taped the magnets around a wooden circle and connected that to an electric drill. I then spun that right next to the entire coil of mag wire that Nick gave me. (connected both ends to the multimeter) It didn't work though... I tried connecting it through the rectifier but that didn't work either. It would be good to get wire of a smaller gauge (thicker wire) and some neodymium magnets. But all that (especially magnets) costs money!
I taped the magnets around a wooden circle and connected that to an electric drill. I then spun that right next to the entire coil of mag wire that Nick gave me. (connected both ends to the multimeter) It didn't work though... I tried connecting it through the rectifier but that didn't work either. It would be good to get wire of a smaller gauge (thicker wire) and some neodymium magnets. But all that (especially magnets) costs money!
Monday, April 14, 2008
The Renegade
Well it seems Richard has me hooked on blogging. Let's just hope the blogger servers don't die on me!
The physics class has embarked on a windmill project, and I became interested and decided to join in the fun. This is my renegade wind power team blog. The team consists of me, whatever, it's still a team!
Info thus far...
To get power from the wind: Connect some windmill blades to an alternator and point them into the wind. Ok, winner for minimum words right there. In reality, the wind turbine turns the rotor inside the alternator which generates alternating current in the armature of the alternator which is located in the stator (including some terms at the end of this). The AC power generated by the alternator gets piped into a rectifier and then into a battery for storage.
The alternator is the tricky part... It requires coils of magnet wire in the stator, and magnets in the rotor. On many the magnets in the rotor are electromagnets (generally coils of wire that are electrified to produce a magnetic field). Permanent magnets make things much more simple, and also more expensive, whatever.
The magnet wire is assembled in coils that alternate wrap direction (not sure on this) and the magnets on the rotor are assembled with the poles from the center to the outside in a radial manner, except that every other one is turned. So magnet A has the north side facing the armature, and magnet B has the south side, and magnet C has the north side, etc.
I'm going to need to acquire magnet wire (Nick will give me some, hopefully), magnets (preferably neodymium magnets), some sort of axle on which to attach the blades and alternator, the windmill blades themselves, and last but not least a tower. I'm going to need a rectifier too, but those cost like $1 at radio shack... which basically means I have to go to radio shack. Sounds like fun to me!
Some equations I ran across:
*total power in wind*
P = rho * A * V^3
where
rho = air density (kg/m^3)
A = swept area (by the windmill blades) (m^2)
V = wind speed (m/s)
*more practical calculation of power derived from wind*
P = rho * A * V^3 * Cp * Ng * Nb
where (these guys are all efficiency, so percentages are used (decimal))
Cp = coefficient of performance (.59 is the Betz limit, generally .1 to .3)
Ng = generator efficiency (alternator in my case)
Nb = gearing and bearing efficiency
What this all boils down to:
Wind speed doubled = 8x the power
Blade radius doubled = 4x the power
Also
746 Watts = 1HP
mph/2.24 = m/s
Some useful links:
http://otherpower.com/otherpower_wind.html (general info)
http://www.awea.org/faq/windpower.html (calculations)
http://www.reuk.co.uk/Betz-Limit.htm (Betz limit info)
http://www.fieldlines.com/ (a forum for assorted alt-power sources)
Some wiki:
http://en.wikipedia.org/wiki/Rectifier
http://en.wikipedia.org/wiki/Alternator
==Terms==
Alternator - produces AC power from mechanical power.
Rotor - the part of the alternator that rotates.
Stator - the part of the alternator that is static.
Armature - the part of the alternator that generates the power (consisting of coiled magnet wire, generally).
Rectifier - changes AC power into DC power through the use of diodes.
Diode - lets current through in only one direction.
The physics class has embarked on a windmill project, and I became interested and decided to join in the fun. This is my renegade wind power team blog. The team consists of me, whatever, it's still a team!
Info thus far...
To get power from the wind: Connect some windmill blades to an alternator and point them into the wind. Ok, winner for minimum words right there. In reality, the wind turbine turns the rotor inside the alternator which generates alternating current in the armature of the alternator which is located in the stator (including some terms at the end of this). The AC power generated by the alternator gets piped into a rectifier and then into a battery for storage.
The alternator is the tricky part... It requires coils of magnet wire in the stator, and magnets in the rotor. On many the magnets in the rotor are electromagnets (generally coils of wire that are electrified to produce a magnetic field). Permanent magnets make things much more simple, and also more expensive, whatever.
The magnet wire is assembled in coils that alternate wrap direction (not sure on this) and the magnets on the rotor are assembled with the poles from the center to the outside in a radial manner, except that every other one is turned. So magnet A has the north side facing the armature, and magnet B has the south side, and magnet C has the north side, etc.
I'm going to need to acquire magnet wire (Nick will give me some, hopefully), magnets (preferably neodymium magnets), some sort of axle on which to attach the blades and alternator, the windmill blades themselves, and last but not least a tower. I'm going to need a rectifier too, but those cost like $1 at radio shack... which basically means I have to go to radio shack. Sounds like fun to me!
Some equations I ran across:
*total power in wind*
P = rho * A * V^3
where
rho = air density (kg/m^3)
A = swept area (by the windmill blades) (m^2)
V = wind speed (m/s)
*more practical calculation of power derived from wind*
P = rho * A * V^3 * Cp * Ng * Nb
where (these guys are all efficiency, so percentages are used (decimal))
Cp = coefficient of performance (.59 is the Betz limit, generally .1 to .3)
Ng = generator efficiency (alternator in my case)
Nb = gearing and bearing efficiency
What this all boils down to:
Wind speed doubled = 8x the power
Blade radius doubled = 4x the power
Also
746 Watts = 1HP
mph/2.24 = m/s
Some useful links:
http://otherpower.com/otherpower_wind.html (general info)
http://www.awea.org/faq/windpower.html (calculations)
http://www.reuk.co.uk/Betz-Limit.htm (Betz limit info)
http://www.fieldlines.com/ (a forum for assorted alt-power sources)
Some wiki:
http://en.wikipedia.org/wiki/Rectifier
http://en.wikipedia.org/wiki/Alternator
==Terms==
Alternator - produces AC power from mechanical power.
Rotor - the part of the alternator that rotates.
Stator - the part of the alternator that is static.
Armature - the part of the alternator that generates the power (consisting of coiled magnet wire, generally).
Rectifier - changes AC power into DC power through the use of diodes.
Diode - lets current through in only one direction.
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