Author Topic: Vawt power Calculations [CLOSED] (Read 6475 times)

xclr82xtc · « **on:** December 08, 2009, 04:35:51 PM »

heres what i got... using the surface area of a cylinder...i think this is right, but what i dont under stand is how does adding or removing blades affect the power output? it doesnt seem like there is a provision for that...or is that what the CP is for in the bottom formula? i did a 40% effieciency.

swept area 4.37795

10mph wind 4.464m/s sea level turbine

wind power availible in swept area

p .5 * rho * a * V^2

p= .5 * 1.225 * 4.37795 * (4.464*4.464*4.464)

p = .5 *1.225 * 4.37795 * (88.96)

p= 238.55

power output predictin at 10mph wind with no deflectors

P = 0.5 x rho x A x Cp x V3 x Ng x Nb

P = 0.5 x 1.225 x 4.37795 x .40 x 88.96 x .758 x1

Pout = 72.32

ok now that i have these numbers, how does adding deflectors affect the equations? you increase the velocity when you add deflectors, but its my understanding you incread the density as well? is this right?

the deflector would be 24 inches taller than the mill, so 7 feet, with a width of 60 inches...versus 36 for the turbine.

thats 3.25160sq/m of surface are to take in the wind, and we are compressing that into an area that is 1.39354 m² to turn the turbine... thats roughy a 3:1 ratio so would you triple the wind speed, and density? not sure where to go from here.

xclr82xtc · « **Reply #1 on:** December 08, 2009, 04:57:08 PM »

wth? i put this in the wind section i thought! lol

sorry.

Volvo farmer · « **Reply #2 on:** December 08, 2009, 05:04:07 PM »

Away?

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:-)

Sorry, couldn't resist. I'm sure there are lots of patient, helpful people here who would love to help you answer these questions. I don't happen to be one of them, but judging on the last two threads you started, you might have about used up all your goodwill already.

Have fun!

xclr82xtc · « **Reply #3 on:** December 08, 2009, 05:15:43 PM »

if i dont figure out how to do them by hand, ill spend $500 on a add on for solidworks and simulate it. wont hurt my feelings any. i prefer Not to do that, but whatever. i need the sim software anyways so i can figure out the best pitch for my blades before i build it

wdyasq · « **Reply #4 on:** December 08, 2009, 05:30:49 PM »

WOW! Somebody who will finally be able to figure out a VAWT ...

I will wait for the result as I don't think the great minds of the past have succeeded.

Volvo, I'll match your amount for a successful VAWT ... and give it 3:1 odds if this duck figures it out!

Ron

xclr82xtc · « **Reply #5 on:** December 08, 2009, 05:46:08 PM »

umm...what?

3:1? lol

no seriously i really need to get this calculation done. because price point anaylysis has it at 47cents per watt right now, running 20 hours a day, and if i can double the output obviously i can halve the price point (also remember thats materials only, im building this myself, and doesnt include the electronics becuase im not having to buy any, actual proce point is even higher)

obvisouly the solution is deflectors, but it dont want to build 15 different versions to get the on that works the best.

xclr82xtc · « **Reply #6 on:** December 08, 2009, 05:56:01 PM »

ok the new calculations using only double the wind speed and increasing the density to 1.5 gives me 700 watts. that not bad i guess, but i really need to figure out what happens inside the deflector.

if you stay with the same 1.5 desnsity, but triple the velocity ( you would need a major low pressure area to make this happen i think, but i think its possible with a big enough deflector) you get 2657 watts...now thats more like it. and this is assuming a 10 mph wind..i can only imagine how many rpm this thing would be spinning...in a 20mph wind, it would implode lol..no jk, but that would be ALOT of power

xclr82xtc · « **Reply #7 on:** December 08, 2009, 06:02:28 PM »

188,357 watts theoritical at 20mph ...ASSUMING the deflector triples the wind velocity and increases the density to 1.5. ntw.. this is with the formula for alternator output, not total power availible so all the deficiencies are already calculated it.

the PMA would melt.. you could turn a GIANT generator though..

and it would spin stupid fast...you guys see now why i want maglev? no bearings to ear out when 2 hundred pounds is spinning 500 rpm

DamonHD · « **Reply #8 on:** December 09, 2009, 01:44:25 AM »

When you say "obviously", from my observation very little is "obvious" about VAWTs or how to optimise them.

I saw yet another failed design just the other day...

Rgds

Damon

wooferhound · « **Reply #9 on:** December 09, 2009, 08:28:42 AM »

He is doubling the prize money . . .

http://www.fieldlines.com/story/2007/10/10/52711/090

I hope you can figure out how to do it

none of us have been able to.

except windstuffnow.com

If I were you I would go ahead and get the $500.oo software

it will save you thousands of dollars in the end.

xclr82xtc · « **Reply #10 on:** December 09, 2009, 08:51:24 AM »

hey and the other guy said 3 to 1..

my idea is that if you put a BIG tunnel surrounding it, and aim it at the blades you do several things,

1- get rid of the blade drag on the blades that are not catching the wind.

2 increase the velocity exponentially

3- increase air density

4 increase RPM (which is why i need maglev its gonna be spinning fast i think even in low wind)

which means power outout increase..t

the problem i forsee now is how do you keep such a large deflector aimed into the wind?

i can see a VERY large tail, OR, i can do it with some kind of eddy current or micro switch setup...ie, a small tail will move, hit the switch, and a motor will kick on and reposistion the deflector..doesnt seem very effiecient to me, but you gotta spend money to make money, so if you have to spend 30 watts to get 600, then i guess its ok. should be a fairly simple circuit to design...

question....

does that prize money still come into play even if i use the local boat manufacturer to build the deflector? i dont have the skills or equipment to build anything that large. i know it says home brewed only..

wooferhound · « **Reply #11 on:** December 09, 2009, 10:13:53 AM »

We have talked about this a lot . . .

http://www.fieldlines.com/story/2003/6/17/73839/3388

http://www.fieldlines.com/story/2007/7/13/221748/030

http://www.fieldlines.com/story/2005/7/11/21517/7456

http://www.fieldlines.com/story/2005/7/11/21517/7456

http://www.fieldlines.com/story/2003/11/22/7365/5340

http://www.fieldlines.com/story/2006/10/10/232638/13

Hilltopgrange · « **Reply #12 on:** December 09, 2009, 11:52:46 AM »

"not sure where to go from here."

Seems to me your design is getting more and more complicated and expensive!

Fitting a tail, shroud ,switches, motors and possibly a controller of some sort, then it is also going to need a substantial tower to get it into clean air as it will suffer from turbulence at low hieghts just like a hawt does. This is going to cost a fortune.

The most attractive asset of a VAWT that I can see is that it doesn't need to yaw or follow the wind! So surly fitting a tail and duct is a step backwards.

What do you think will happen to your "deflectors" when they get hit by a storm?

The most successful turbines use the KISS approach (keep it simple stupid)

There is a much simpler and cheaper solution to your problems, that will increase the rpm and the output, it will keep the costs down and is proven to work, just build a HAWT you don't need ducts or motors or switches or any other cr*p. The design is very simple with minimal moving parts and is scaleable to suit the output you want it has been well proven and most importantly it works.

I think you will eventually come to see why a 3kw vawt is never going to be practical. You could build a 3kw HAWT for a fraction of your proposed design costs and in a fraction of the time.

Why do commercial wind farms use HAWTs?

Why do they not use ducts ?

When did you last see a successful wind farm use VAWTs ?

If you are looking for a design challenge try and design an improved method for furling a HAWT.

Just the way I see it.

hilltopgrange

"There are none so blind as those, that will not see"

xclr82xtc · « **Reply #13 on:** December 09, 2009, 03:08:45 PM »

i see your point bro, i just feel like a VAWT is a better way to go..remember i live in a low wind area..when you do the math, you get more power from the wind with a vawt than a hawt, dont jump off on me, i mean that you can get the same amount of swept area with a smaller vawt as a larger HAWT...the reason for the deflector is to increase the efficiency of the turbine. i cant physically build a deflector big enough to double the power of a HAWT (unless it was a small HAWT) but for a smaller vawt that has a 36 inch diameter vs 20 foot diameter..its just a matter of building a mold. not to mention that the deflector will eliminate the unpowered side from having to fly into the wind.

really simple bro, a simple vawt deign, inside a box...and the box just happens to have an opening the increase air flow. there is no gear box, no bearings, ..really nothing to go wrong, just a vawt with some magnets attached to it, and a steel plate on the bottom that doesnt spin that holds the coils..the center "axle" that the hawt spins around will be the support for the deflector so it can spin into the wind.

maybe i cant explain it well...maybe im making it more complicated than it sounds...im working on the final cads, ill show you guys eventually.

Hilltopgrange · « **Reply #14 on:** December 09, 2009, 04:42:44 PM »

I really don't want to p on your parade so I wont jump all over your last post, but I have to comment on the last part and then im finished with it.

"really nothing to go wrong, just a vawt with some magnets attached to it, and a steel plate on the bottom that doesnt spin that holds the coils..the center "axle" that the hawt spins around will be the support for the deflector so it can spin into the wind."

In other words rather than build a vawt you have decided to build an eddy current brake....you really have done a lot of research on this.

Best of luck with it, your sure going to need it

hilltopgrange

Perry1 · « **Reply #15 on:** December 09, 2009, 05:00:20 PM »

***PUBLIC SERVICE WARNING*****

Sorry to have to do this but this is a public forum and others may be reading this to help them understand wind turbines. Looking for real understanding on how they work.

Take this thread with a grain of salt. All the calculations included have been grossly wrong to this point and just about every turbine concept proposed is NOT how one would make any sort of wind turbine.

Do your research and consider your sources.

Sorry but it had to be said.

Perry

xclr82xtc · « **Reply #16 on:** December 09, 2009, 05:06:46 PM »

how the hell is it an eddy current brake? since when is an eddy current break and a PMA the same thing?

xclr82xtc · « **Reply #17 on:** December 09, 2009, 05:13:44 PM »

then do the calculations and give me the right answers smart man...

please tell me why it "wont work" and why everthing this is wrong.

its amazing how you people keep telling me it WONT work, yet im sitting here at a computer with 15,000 dollars worth of fluid dynamics software on it, and its telling me it will...

do you even KNOW how to do the calculations for the defelctors perry? they are very very complex, and NO, I DONT know for sure how to do them..thats why i said they are best guess. The calculations WITHOUT the deflectors are right.. thats second grade math.

please prove me wrong...

maybe you should get off the hawts and think outside the box. sticking with the same stuff all the time doesnt accomplish anything. why the hell are you people so frightened of change?

stop saying how something wont work...take a step back..and try to come up with something that will. either help, or STFU.... PERIOD..END OF STORY.

Hilltopgrange · « **Reply #18 on:** December 09, 2009, 05:21:43 PM »

when you place a non rotating metalic component within the magnetic circuit! thats how.This is very basic stuff similar to your claim about axle flux machines cogging! just plain wrong.

To demonstrate take a piece of aluminium and move a strong magnet quickly accross the surface and feel what happens the same happens with steel.

You really should spend sometime reading past stories!

hilltopgrange

xclr82xtc · « **Reply #19 on:** December 09, 2009, 05:24:29 PM »

THERE IS NOTHING THAT ISNT ROTATING!!!!

how many times do i have to explain this design...its all rotating everything excpet the very bottom lev magnet and its seperate from all the other magnets...along with the second lev magnet that is..

ugh..i give up.

News:

Author Topic: Vawt power Calculations [CLOSED] (Read 6475 times)