Author Topic: Disk-Style, Vertical Axis Wind Turbine 44% efficient? (Read 807 times)

aogden · « **on:** June 02, 2005, 08:24:58 AM »

Is it possible to get 44% efficiency from a turbine?

Please check these claims out: http://www.fuellessflight.com/windturbine.htm

Editors note:

This seems to be turning into a "ridicule Bob Hunt" thread. I have made it read only so it doesn't turn into a flamefest.

Bob if you would like to respond to this thread, I think you might consider a Diary entry.

BeenzMeenzWind · « **Reply #1 on:** June 02, 2005, 02:36:00 AM »

I asked a friend of mine, who is a sailing nut, and he confirms the bit of the article about oyster fishing. Apparently your boat has more pulling power if you set your sails in a drag configuration but it doesn't go very fast.

As for the turbine itself, it's been so long since I did the RAF aerodynamic principles course that I couldn't even guess whether the thing would work as advertised.

Clever idea though. Bet it's noisy with those moving flaps.

tecker · « **Reply #2 on:** June 02, 2005, 02:48:04 AM »

Too many moving parts

XRay · « **Reply #3 on:** June 02, 2005, 03:26:31 AM »

Perhaps, 100% wind passes the turbine in its sweeping area and the flaps will capture 44%. Pure drag tsr<1

They don't say what type of horizontal axis wind turbine they compared it with, it must be with a drag type to. Also it must be very noisy and mechanically weak.

I think you better forget this turbine.

Greetings,

Ray

drdongle · « **Reply #4 on:** June 02, 2005, 04:57:09 AM »

If I remember correctly 58% is the maximum possible efficiency of any wind turbine, or do I remember wrongly?

Kevin L · « **Reply #5 on:** June 02, 2005, 06:01:12 AM »

Notice how slowly it's spinning in the video. That's because it's unbalanced. If this were spun up in more then 5 mph winds (like 25mph) it would fly apart. Also allot of energy is expended in fighting gravity & raising those flaps. A guy in like Minnesota or N. Dakota made a VAWT that was like a big Merry Go Round that had a Camshaft moving like 30 blades around the circumference. The blades were vertical but it also had allot of frictional loss. We all know how brutal winds can be and when there are allot of expensive replacement joints, it become impractical to make it light, strong and cheap enough. Those three words are not synonymous. I have been working on a large diam VAWT mill for quit some time (6 Years) and have not figured out how to get past the wind gusts that can be so brutal to this type of device. That's one advantage to HAWT is that its bending moment is such that it doesn't place allot of stress on the drive bearing and gearing, but on flexible much cheaper blades. Where the wind gust force of a VAWT runs through the entire system placing allot of stress on everything. Still plugging along in Central Ohio.

Kevin L.

NG · « **Reply #6 on:** June 02, 2005, 06:48:45 AM »

It does look good for the speed but if the guy wants to use it on a boat it won't hold up very well. If it was designed fixed wing and the air was funnelled onto the fan blades it could be made sturdy and get higher speeds. It also looks way too ugly to get any land use, imagine a huge one of those outside your house.

whatsnext · « **Reply #7 on:** June 02, 2005, 07:30:42 AM »

You would never get any high speeds. Without lift the 'tip speed' would never exceed wind speed. This idea would work no better than the wheel barrow mill posted here recently. Plus it's way over complicated. Hopefully any potential invester will demand a working model of the boat before writing a check. The guy also is wrong about the sailboat experiances. The fact that the boat is faster while the sails are in lift configuration clearly show that they are producing more power. That's why the boat is faster. When you use a sailboat as a dredge the boat slows enough to prevent the sailors from taking advantage of the increased apparent winds and is forced to sail downwind where only drag will work.

John.........

electrondady1 · « **Reply #8 on:** June 02, 2005, 01:50:45 PM »

i think a folding design is an improvment over a conventional drag unit. i like how he uses gravity to open up the vane and wind pressure to collapse it. his mechanism is clever but it might be kind of noisey. i think i just like the bottom side, now where's my sketch pad.

whatsnext · « **Reply #9 on:** June 02, 2005, 02:05:40 PM »

A folding design would likely be less effective. Because the parts have mass and the pivots have friction they will open and close later than they should. Plus, The energy involved in opening and closing them is wasted. I doubt drag VAWTs will ever be cutting edge but who knows.

John........

electrondady1 · « **Reply #10 on:** June 02, 2005, 08:12:34 PM »

what i'm looking for is semi indestrutable not cutting edge in fact i want a non cutting edge

aogden · « **Reply #11 on:** June 03, 2005, 01:09:20 AM »

It seems there is another varient by their marketing group (or person)here: http://www.encorecleanenergy.com/default.asp?c=2250

Balance is cacelled by dual counterrotating disks, but this adds complexity, humm.

aogden · « **Reply #12 on:** June 03, 2005, 01:19:44 AM »

Interesting range of comments! I would at least like to acknowledge the unique design and have been thinking that it could be altered to be operated with sails made of lightweight materials. This would mitigate the mass and moving parts problem. I am not focusing on noise initially, there are some things that could be done if in fact the concept is sound which I'm still not sure of. My 3 cents worth, beauty is in the eye of the patent beholder -;) I Still have the wind turbine bug, something like gold fever I'm told! Cheers, Adrian Ogden - Napa Valley CA.

BeenzMeenzWind · « **Reply #13 on:** June 03, 2005, 04:21:03 AM »

Maybe that's what he meant? I'm not a boat enthusiast, so.....

rotornuts · « **Reply #14 on:** June 03, 2005, 09:21:49 AM »

I think the folks building that unit just have a fever. BTW, it's not an entirely new idea just a variation on quite an old one. Why is it that these guys have never mated one of these units to a generator and logged some data?

Mike

whatsnext · « **Reply #15 on:** June 03, 2005, 10:02:42 AM »

Because it's a dumb idea and won't work. His water wheel concept is particularily idiotic. For some reason he's fixated on the vertical axis concept but if he just rotated the water wheel 90 degrees the entire wheel would be in the water stream instead of just a small part. Also, he could then use a fixed prop that could look like something off a 1900's freighter. Of course then his 'idea' would be tough to patent but it would at least work. The stupidity of his speedboat idea would be even more galling if it ever got past a pencil on paper doodle which it won't. The guy is trying to solve a problem that does not exist and other than an interesting piece of lawn art I don't see anything worthwhile. Could someone please explain, to me, how this makes even the slightest sense? I could be missing something.

John................

kitno455 · « **Reply #16 on:** June 03, 2005, 11:51:34 AM »

agreed, john.

the whole reason i find vawts interesting is that there is less data about them already. hawts have benefitted from all the prop and wing airfoil research that we have been doing for the last hundred+ years, but they are basically an exercise in details and manufacture.

so, i have no problem playing with silly ideas, but i dont preface the description of my inventions with 'this will change the world'. instead i choose to say, 'this is silly, but it works'

just learn to ignore the marketing drivel, and get a kick out of the device.

now, all that said, the biggest (only?) advantage a vawt has over a hawt, is simplicity since they dont have to furl or have a tail there is only one moving part. but to get them into the same eff% as a hawt, most designs add those very things, so your comments likely apply to all vawts.

allan

huntband · « **Reply #17 on:** June 04, 2005, 09:43:42 AM »

I am Bob Hunt the inventor of the subject vertical axis wind turbine and was asked to reply. I would first like to state that the turbine makes virtually no sound because of its high torque, slow rotation speed and due to hydraulic rams that control the shutters. The rams act as hydraulic pumps that harness the kinetic energy of the opening and closing of the shutters, so the energy is beneficially added to the shaft output power via a hydraulic motor. Gravity causes the shutters to open as the pairs of shutters are connected by gears that counter-balance their mass and the lower shutter is heavier to actuate opening (thereby lifting the upper shutter) and then the wind's force closes the shutters as they rotate ninety degrees into the wind. So they are not working against gravity -- they are actuated by the earth's gravitational pull. You can open and close five feet wide by twelve feet long by two inches thick composite shutters geared together weighing almost a hundred pounds each with your finger tips; and, they actuate with any wind whatsoever because of their large surface area, regardless of the wind's direction. The high torque is derived from these large surface area shutters being extended out on a long lever arm. The current model being tested has six pairs of shutters with three open to catch the wind and with three closed to reduce negative drag all the time during operation. We have been very pleased by its performance and have not experienced any structural problems during high wind speed operation thus far.

XRay · « **Reply #18 on:** June 04, 2005, 01:40:20 PM »

Hi Bob,

Interesting explanation.

Can you explain this 44% efficiency and the comparison to an efficiency of 21% for a conventional horizontal axis wind turbine?

My guess is this HAWT is a drag type?

Source: http://www.fuellessflight.com/windturbine.htm

Greetings,

Ray

kitno455 · « **Reply #19 on:** June 04, 2005, 05:52:44 PM »

but bob, there is no free lunch. the hydraulics (and gravity) that resist the closure of the moving plates translate into a wind-brake as that set of plates turns into the wind. this windbrake counter acts the force provided by the hydro motor.

in fact, i am willing to bet that the friction of the hydro pistons, losses in the hydro motor, and speed decrease from still having the flaps up when you turn the corner, add up to noticably more power than the shaft gets from the hydro motor. in fact, it HAS to. law of conservation of energy.

you would be better off letting the flaps slam shut as fast as possible, and catch them in the last second with a rubber bumper, or use a tail and gearing system to close them faster. less friction and drag losses that way.

allan

whatsnext · « **Reply #20 on:** June 04, 2005, 06:26:49 PM »

Allan, You're giving Bob way too much credit. Drag VAWTs are silly for any number of reasons. They can't ever work unless you don't care how much the minimal power you get out of one costs. Torque is worthless without RPM and drag VAWTs don't spin fast enough to produce meaningful power. Look at his speedboat again. I didn't want to mention it before but now that Bob is here posting the gloves are off. The only way that speedboat could operate is if Bob has invented an over unity device which, I'm just guessing, he has not. The drag caused by the air intake alone could not possibly be overcome, and allow the boat to move foward, unless the turbine was way over 100% eff. Look around his site. He claims to have plans for an airplane that uses no fuel but can carry huge payloads. I don't even know where to start with this dope so I won't bother.

John........

XRay · « **Reply #21 on:** June 05, 2005, 03:23:40 AM »

That's way I asked him to explain the efficiency stuff. There is just to mush bs in all this.

The biggest advantage of a VAWT is the minimum amount of mechanical components, so the reliability is higher than a HAWT mechanically speaking.

This thing has more mechanical components than a HAWT so its a you name it thing.

Sorry Bob, it not personal.

Greetings,

Ray

electrondady1 · « **Reply #22 on:** June 05, 2005, 06:24:50 AM »

bob, valient of you to defend your design.time will tell it's worth. utilizing gravity and wind pressure to modify the profile of of your vanes is very clever. congratulations.

kitno455 · « **Reply #23 on:** June 05, 2005, 08:26:41 AM »

think you went a bit overboard there john.

we are talking about this one vawt. i did not surf his site beyond that, and have not seen this speed boat, and dont care about boats
torque most certainly has value, even at low speeds. low speed engines with a step up drive can run all sorts of high-rpm devices, with the same abilities as a direct drive high rpm motor. now, of course we are talking wind turbine, so that is different, but lots of folks run savonious for water pumping applications. simplicity and slow speed in both engine and turbine leads to longevity.

now, that said, this thing loses most of those advantages

allan

whatsnext · « **Reply #24 on:** June 05, 2005, 09:56:09 AM »

Allan, I don't think I went overboard at all. Looking at the rest of Bob's site is important because it shows where his concepts are coming from and that 'from' is an utter lack of understanding of the concept of conservation of energy. All of his devices would have to create their own energy for them to work any better than than allready established, and much simpler, ones or even at all. Patents are designed to protect intelecual property he doesn't need one because his designs are not very intelectual. If any of the folks here want to make copies, for their own use, of Bob's wheel they are free to do so and see for themselves. I just wish guys like Bob would publish performance figures before asking people for money. I would have had a good laugh out of it if not for that.

John......

aogden · « **Reply #25 on:** June 05, 2005, 11:46:05 AM »

After speaking to Bob I have learned that he will be testing a ten foot disc VAWT in the next couple months, my understanding is that the 44% efficiency is purely mathmatical. It is my hope that he will share his findings with us. It distresses me to see so much slander in this forum. This makes me hesitant to post my ideas as "idiotic" as they might be deemed. That being said I would be interested to review Bob's calculations as well. Adrian- Napa CA

PS: I initiated this posting in the hope of responsible peer review, I'm disappointed.

TomW · « **Reply #26 on:** June 05, 2005, 12:22:17 PM »

Adrian;

Let me point out that extraordinary claims require extraordinary proof.

Folks here shoot from the hip and I believe most do so honestly, if not in a very politically correct manner.

Anyone who has done any real world mathematical analysis versus hardware comparisons should know better than to make claims based on math without actual data to show a fantastic divergence from generally accepted values.

Frankly, I thought these guys were quite gentle compared to other threads.

When you ask for feedback you really need to be prepared to listen to that feedback without becoming emotionally involved in it.

Besides we all know you need to wear nomex underwear on the internet because we have every type of user you can possibly imagine. Geniuses, jerks, morons and some who just hate you for trying. Its the spice of life.

If you just want reassurance that you are doing something great you are probably in the wrong place.

Cheers.

TomW

whatsnext · « **Reply #27 on:** June 05, 2005, 01:30:53 PM »

Adrian, I hope your friend Bob posts his results here. I'm also hoping that his results can be repeated by his peers. I'm also quite sure that no one would attack you for your ideas until you start making unfounded claims and then start asking for money to waste on them. It's nice to know, now, that you have a connection to this guy. You might have mentioned that in your first post. You know, just to be honest and all.

John.......

rotornuts · « **Reply #28 on:** June 05, 2005, 01:51:05 PM »

I've posted some pretty rediculous stuff here and have done my best to defend those ideas including working models and pictures. I've seen nods of approval and also the big thumbs down but never had a strip torn off me and I believe it's because I purposely put the ideas up here to recieve feedback good or bad and I have never made rediculous performance claims. My math may be lacking but a couple minutes with the calculator tells me that at a TSR of 1 this 10' unit that is being built will in a 15 MPH wind have about a half a second to deploy it's hydraulicly assisted flaps do it's work and start closing them again, every revolution. Hmmmmm. That's going to be some hot hydraulic fluid in short order.

Mike

wdyasq · « **Reply #29 on:** June 05, 2005, 02:14:01 PM »

Well, it you are looking for charm school remarks, I suggest you go somewhere else. I looked over the website and saw stuff I had drawn in the mid-late 70's.

One of the most interesting windmills using drag and lift is the Cory Jib Windmill. You should take a look at it and learn a bit. Not only does it capture power both upwind and down, it grabs a bit in the 'jib' and self furls with crude but effective mechanisms.

I do hope we see some more of these thoughts. Anything that gets near the Betz limit with drag alone interests me. Things that can get power out using hyrdaulics - which are terribly inefficient, intrigue me too. To see both in one unit will be a treat.

Ron

kitno455 · « **Reply #30 on:** June 05, 2005, 02:54:19 PM »

"PS: I initiated this posting in the hope of responsible peer review, I'm disappointed."

why are you disapointed? you asked, and we told you. we each used different ways, john said 'look at his other ideas, this guy (and his designs) have a basic math problem'. i said 'look at the specifics of conservation of energy, this thing wont work any better than the simpler savonious', and someone else (electrondaddy maybe?) said 'nice design'

there. you got your peer review. 2 out of three guys on this board say the design stinks. you friendship or whatever with the inventor has blinded you to the reality of getting exactly what you asked for, people's opinions. sorry, but him being nice via email and having the stones to come and comment here does not mean that his design works, it means he social-engineered you.

allan

electrondady1 · « **Reply #31 on:** June 05, 2005, 07:18:18 PM »

well, i searched for the cory jib windmill and couldn't find it, but it sounds interesting. in defense of this forun, the guys here pull no punches, if you build something lame there gonna' let you know .a few months ago danb and windstuff ed were comparing numbers ,hawts vs vawts. ed mentioned that if a drag type didin't have to pull the convex side into position to catch the wind efficiency would outstrip a hawt. i've been sketching a lot lately with that in mind. there are lots of ways to do it but they all have a tendancy to get complex and fragile.it had not occured to me to simply use gravity to pull the vane back into a "power" position. if one were to use a conventional part cylinder shape and hinge it horizontaly at the top, as it rotates, the convex side would rotate up(due to wind pressure) and the profile would be reduced( i think ) kind of a furling effect. there would need to be a stop built into the vane or support shaft in order to position the vane in an optimum position. it might be worth exploring. i'm not shure about all the hydraulic stuff on bob's design. it seems complex .

whatsnext · « **Reply #32 on:** June 05, 2005, 08:36:39 PM »

electrondady1, How about this: just cover the upwind blades with a shell of some sort. Remember that this cover will have to turn with the wind but a big tail sould take care of that. I still don't see why so many of us here think that VAWTs are so much 'simpler' than HAWTs. If you are produsing X amount of power you are going to have very similar forces caused by drag. So how is a VAWT simpler. HAWTs have much smaller cross sections. The bearings can be placed near the center of load so it is easier the handle both lateral and radial forces. Do you really think all the engineers working on huge HAWT farms just 'have not thought of a VAWT'?

John.........

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Author Topic: Disk-Style, Vertical Axis Wind Turbine 44% efficient? (Read 807 times)