Author Topic: Fin Shaped Wind Turbine (Read 9345 times)

MattM · « **on:** December 29, 2010, 02:59:29 AM »

I was looking at the Dyson fan and thought of how it probably would work for a wind turbine in reverse, but thought to my self that it would be needlessly complex to manufacture. Instead one could focus their effort on the hardest part of the idea (the blisk impeller) and simplify the rest. I settled for a fish fin shape from the side and a tear drop shape when looking at it from the top. It's simple save for the need of a 3-dimensionally manufactured blisk. Rather than using hard materials for the outer skin it would be possible to use fabric stretched over the frame.

Below is an attachment of a picture demonstrating the basic idea. I'm not a machinist so it is impractical for me to build. But I am hoping the general idea might spark someone with more talent to run with the idea. The part I like most about the idea is that it should be easy to scale up in size.

Norm · « **Reply #1 on:** December 29, 2010, 08:28:43 AM »

Things that work in one direction usually don't work as well in reverse
if at all .....the wind might not follow that path just because you want it
to go that way.......

tanner0441 · « **Reply #2 on:** December 29, 2010, 11:32:33 AM »

Hi

I once had a Dyson vacuum cleaner; (don't want another one) but one thing that is evident to anyone with any knowledge of fluid dynamics is it relies on high velocity air flow. The motor spins a a phenomenal speed, compared to a wind turbine and the air flow through the duct is also very high, compared to the wind, hence the small cross sectional area of the duct. You will find those shaped blades appear in car turbos, again using high pressure high flow rates.

Wind turbine blades are designed to take power from moving air, Dyson blades, and aircraft propeller blades are designed to put energy into the air.

Plus to do it properly the turbine stator, and rotors are designed with the blade set in the equation.

Brian....

(Unrelated but, I just love the spell checker on here)

MattM · « **Reply #3 on:** December 30, 2010, 03:04:47 PM »

From what I gather from Dyson designs is he likes to simplify designs for less moving part size. I think his frame of thinking can be reversed for a wind turbine design. My idea is to focus the air pressure into a smaller area not unlike a parabolic solar collector focuses light energy into a central focal point. I'm trying for a simpler overall design to build that doesn't involve crafting the wood or metal turbine blades. The lightweight blisk could be stamped out of metal or molded from several lightweight materials for simplifying manufacturing.

After a little more thinking the idea could be further simplified with a parachute design. The bleed hole in the top of the 'chute' would be the location of the blisk. Air pressure across the frontal area would force the air through the bleed hole and against the blisk. The chute need only be supported by a tripod set of arms extending off the pivot point. Rather than using a wind sock design, I'm thinking more of a bowl shape. As the chute diameter increases in size so does the pressure going through the focal point of the bleed hole. The chute would be destructible if winds overpower it. Replacing the chute is far cheaper than the other parts.

Rover · « **Reply #4 on:** December 30, 2010, 04:27:10 PM »

Hi MattM

My first thoughts at looking at your really nice picture of a funnel fed turbine are:

1. You will be creating a massive amount of turbulence before it hits the fan, which will reduce the effectiveness. A lot of the wind will simply bounce around inside the funnel, either losing energy or just bounce out.

2. You will need very strong arm supports , since you will robably have wires , some for of alternator/generatorand transmission wires behind the fan

3. using a "soft" funnel approach , also means the funnel itself will absorb energy

I'm all for imaginative ideas, I'm pretty sure this has been tried before, however keep thinking.

gotwind2 · « **Reply #5 on:** December 30, 2010, 05:45:24 PM »

Matt.

There may be some merit in your design.
However it is very easy to run away with a 'new' idea, I do it myself constantly

I think this is what the Fieldlines board is here for, and personally I applaude it, love it.
Most things have been done though unfortunately, as the respected contributors here will I'm sure explain.

Keep going, the rest of the worlds massive companies with massive resources are doing the same, I know for a fact, Japan in particular.

I'd like to see motor racings formula 1 engineers (The best in the world with Aero packages/ kinetic energy recovery systems e.t.c) come up with a solution personally, rather than burning up fuel on a test track at 4 m.p.g - I have written to many racing companies on the subject, but alas nothing..
Anyone know Bernie Ecclestone personally?

I don't mean to hi-jack the thread on that matter $:-\$

MattM · « **Reply #6 on:** December 30, 2010, 06:15:26 PM »

True, this guy had a similar idea, only using a cone feeding in and an axial-flow turbine that uses another cone to focus the air onto the thin blades. I was aiming at a simpler design using a single-piece blisk.

http://www.rexresearch.com/green/green.htm

fabricator · « **Reply #7 on:** December 30, 2010, 06:18:32 PM »

That looks as far from simple as you can get, but I've never let anybody else talk me out of any of my crackpot ideas, a lot of folks thought Tesla was a crackpot too.

tanner0441 · « **Reply #8 on:** December 31, 2010, 05:20:47 PM »

Hi

don't want to damp your enthusiasm but when the wind hits your funnel the angle of incident and reflection are the same, the air can't come back on itself so it is going to create swirls and vortices's the amount of air going through the hole at the back will be minimal, think what happens when water goes down the plug hole in the sink.

There is a design for a ducted turbine using a shallow venturi but the advantage is not worth the effort. Why not build a small turbine that works, collect data and you have a base set of figures to work with, then you can measure any gains.

Brian.

MattM · « **Reply #9 on:** December 31, 2010, 08:56:48 PM »

The wind will push against the blisk proportionately to the amount of surface area in front of the chute collector. Your bigger chute will collect more wind energy. We could care less what vortexes form around the outside of the chute, we're only concerned with the pressure and air speed at the focal point.

fabricator · « **Reply #10 on:** December 31, 2010, 09:29:26 PM »

Ok, lets start at the most obvious trouble spot in your picture, you have the rotor at the small end of the funnel with a long drive shaft going to the alternator on the yaw tube, how will the rotor end of the shaft be supported by a fabric funnel? There will need to be a bearing there now matter how light the rotor is.
Trouble spot two, I suspect the scale of your picture is WAY off, in order for such a configuration to make any amount of meaningful power my thinking is the size of the rotor would need to be on the order around ten times the size of the alternator.

tanner0441 · « **Reply #11 on:** January 01, 2011, 11:56:22 AM »

Hi

have you thought about putting a small motor next to the PMG to keep it turning in times of low wind.........................

Brian

MattM · « **Reply #12 on:** January 04, 2011, 11:36:45 AM »

tanner, har har

fabricator,

The driveshaft could be a support arm for the PMG for that matter. The idea is to allow space in case of a failure for the fabric to detach from its outer perimeter attachments and simply fold back around the blisk housing, not unlike a flag blowing in the wind. The idea is to use the air pressure that builds up in the chute to drive the single blisk. This is applying the 'concentrator' principles - already used in solar collectors - to wind. The principle is to drive up wind speed where it is needed, at the blisk, which in turn increases the rpm's at the PMG. Every doubling of the air speed increases the power exponentially, right? (Now I'm not talking across the face of the chute, I'm talking air speed at the blisk.) So it makes sense to funnel that power to a single point rather than having those huge mechanical arms moving around. When a turbine blade breaks you have a huge potential for collateral damage. When this thing breaks you minimize the risk.

The blisk has to be sturdy, but it doesn't have to be as sturdy as one used at the end of a water chute in a hydroelectric turbine. The blisk has revolutionized aircraft turbine design because of its simplicity. Fewer parts, simpler to manufacture. Swap out one part after a failure. Much simpler to machine a blisk than it is to manufacture one turbine blade, let alone a matching set of three!

The idea of using a fabric chute is for creating the break point during a storm. Rather than losing the entire assembly, you replace the chute. It's inexpensive. It's very light. It's simple. It can be attached to the blisk's chute-housing with what resembles a hose clamp. Low tech. As the surrounding chute size increases the exposed frontal surface area increases, which likewise increases the amount of force and its corresponding air speed that travels through the blisk's front opening. We know no matter how good your design you'll always lose approximately 40% of your air flow from the air routing around your turbine; doesn't matter if its my design or a traditional one. Air that is forced through the blisk will follow the same principles of uncompressed fluid dynamics as any other turbine, its not reinventing the process. You want high rpm's, keep the blisk small. You'll lose some torque to get the higher rpm's. Scale the blisk size up to increase the torque potential. Blisks are tough, incomparably stronger than a traditional turbine blade! (Look how tough the Motorwind disk is at only a 25cm diameter; a blisk would be even stronger.) The point is that the single blisk construction is simpler and more mass producible than the current method. It can be milled, molded, or cast. Blisk sizes and their material composition would be easy to categorize and standardize. This would make it much easier for industrial types to manufacture and market DIY kits.

I've found similar ideas, they use solid shrouds and traditional turbine blades. (i.e. WindCube) That is not practical for the DIY crowd.

tanner0441 · « **Reply #13 on:** January 04, 2011, 04:07:34 PM »

Hi

The shape of your funnel is too acute, if you look at the inlet scoops on water turbines they are long slender shapes to promote laminar flow, lamina flow in a fluid has the most work in it.

I have a small hand held anemometer, one of the little turbine types, I held it into the wind and held various funnels in front of it and the reading dropped. Try thinking in microwave RF terms. to collect or radiate the RF energy you have to impedance match the end of the waveguide to free air with a horn radiator, the shape and size of the horn is critical.

Your collector would need to be much longer and more gently shaped to be of any advantage. The shape you propose would stop the air, (gas masking) which in turn would stop the air following it, this would form a big bubble of stationary air in front of the scoop the following air would then go round the outside. Yes you would develop a positive pressure against your collector but very little of it would go through the hole in the middle, and any that did would have no energy in it.

Try dropping a few potassium permanganate crystals in a stream and put a model of your device in the trails and watch what happens. I still say make a small model turbine take readings and work with the figures.....

Good luck with it.

Brian.

MattM · « **Reply #14 on:** January 05, 2011, 12:43:44 AM »

What you are alluding to is called the venturi effect. Until you reach Mach 1 airflow the air will compress through the hole and it's velocity will increase. At Mach 1 the air becomes incompressible (because it's now treated as a fluid rather than a gas) and the pressure drops after said choke point. Basically your mass flow of a liquid is limited to the size of the chokepoint and the rate it moves at Mach 1; any higher speeds decreases the pressure on the exit side of the choke plate accordingly. Interestingly you can increase airflow through the chokepoint by suction on the exit hole, but only if that airflow at the chokepoint remains subsonic. Luckily we won't hit Mach 1 airflow and our air will remain compressible. If you couldn't compress air then our furnaces would have a hard time moving air long distances. So I agree you will lose some energy potential going through the chokepoint. I disagree it will be zero.

MattM · « **Reply #15 on:** January 07, 2011, 02:42:48 PM »

I was asked why the blisk is so wide at the base. The bottom of the blisk is a circle shaped flat plate. Air is compressed through the chokepoint at which point the air speed drops substantially. The blisk changes the air direction perpindicular to it's original flow. As the air exits it picks up speed. Any energy stored as compression will be released. We don't want decompression to take place until after the airflow direction is fully perpidicular. Think of those little spinning fireworks you nail to a fence post. Realistically, you will need significant wind speed to truly compress airflow through the blisk housing. I'm still researching how much is enough, but it's more than I was hoping.

Kwazai · « **Reply #16 on:** January 07, 2011, 02:57:40 PM »

don't think it has to be that complicated- my .02$

Mike

MattM · « **Reply #17 on:** January 07, 2011, 04:51:21 PM »

Okay I got Bernoulli's principle wrong. Air is not compressible until you reach supersonic flow. So the airflow through the chokepoint will increase proportionately to the airflow into the widest point. That's far better than compressing it. If the air compressed we'd be losing way too much energy on the discharge. So as long as the discharge provides a vaccuum to keep resistance at the chokepoint minimal it should work.

ghurd · « **Reply #18 on:** January 07, 2011, 05:04:45 PM »

There was a guy... who did the same general idea... but Big.
And memory is often incorrect...
but I think...
his vertical part was basically HAWT blades,
the generator was connected with pulleys and a belt to an Ametek (definitely),
he was on the shore of one of the Great Lakes (Erie?),
he posted on a wind forum,
his videos were on U-tube,
and it did work pretty well!

Not much to go on.
G-

MattM · « **Reply #19 on:** January 08, 2011, 09:52:21 AM »

Thanks, ghurd. I'll scour the youtube.

joseba1 · « **Reply #20 on:** January 12, 2011, 07:06:05 PM »

Hey Matt,

I think if you don't have a lot of equipment and/or expertise the way to go is to build small, simple, cheap models to test your ideas, the simpler, the cheaper, the better. Keep in mind that in fluid mechanics small works the same is large. Eventually your knowledge will grow and you will be able to intuitively predict performance. Nothing you produce early on has to be a world beater it just has to prove concept by working at all.

Once you have something that works you can go on to the next phase which is: Can it be produced at a reasonable cost? Will it be robust enough to last?
Are there other things out there that do the job as well or better?

I personally like paper, masking tape, matte board, old sheets, wire, dowel rods, tooth picks. Any available fan will give you a reliable constant wind stream. The best part of it you can have some fun in the process.

Having said all that, I think it'd be advisable to get your mast out of the air stream and elongate your funnel to at least a hemisphere to keep the air from backing up in front. Also look into vortex generators. They use them on aircraft to entrain air over control devices. You could use one on the mast to get the air to circulate in the direction that you want ahead of your impeller.

good luck j

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Author Topic: Fin Shaped Wind Turbine (Read 9345 times)