| T O P I C R E V I E W |
| gotwind |
Posted - 30/03/2008 : 20:11:15
Forum member Windymiller kindly sent me his latest blade design, he urges use with caution.
He writes:
The cross section of the blade is of an aerofoil.
The faster the blade spins....the more lift it gets
The black plastic sides enable the back side of the blade to give more lift.
Without them low air pressure (lift)would be less....the air would simply "spill" over the sides.
Pitch on blade is adjustable.....it really does work.
The aerofoils are made of plywood glued together
Overall with 4'6" paddles 8" wide
Arms are 1/2" round spring steel mounted on bicycle hub for test purposes.
WARNING.....bare in mind the weight of these paddles are quite heavy.
Spinning at high rpms creates enormous kinetic energy...so be carefull if coppying the idea.Cheers...WM |
| 10 L A T E S T R E P L I E S (Newest First) |
| windymiller |
Posted - 01/04/2008 : 08:55:22
Thanks again everyone for your replies....appreciated.
Im glad salsams concept was shown.....to me hes just awesome with his off the wall ideas.,,id love to see it work in real life, it would be a great experience..
In answer to Bens question(can it be used as a vawt)i did a quick experiment with a "u" shaped brackets to hold the paddles on the ends of the rods....in effect its construction enabled it to be used as a VAWT.
It took forever to start up and didnt really speed up much.
But ive got a feeling with lots of paddles positioned along a rotating vertical shaft might improve the performance...again i dont know?
With paddles used in a HAWT they can get continuous consistent lift when rotating.
My mind tells me the Vawt lift would vary wildly on each rotation...im not sure...its alot to think about.
The reason for setting out and using the paddle design was simply because i wanted a blade that produce a large amount of torque ( torque eaquals force x radius )
Given that the conventional blades get progressively narrower towards the end ....my mind told me its torque was being gradually reduced ,
After reading about wind behaviour...im a great believer that to extract maximum energy from the wind you must not try and stop its movementor /journey/direction
The paddle design sort of avoided this because reletively speaking it caused little obstruction to the winds movement/journey/directionj,and causing a reduced trail of turbulance.I could be wrong with my theory.
sorry for rattling on but i am trying to be clear to anyone whos interested what my mind is seeing.
MattM ive read your idea and im "chewing on that one ...ive got to think it through before giving you an answer....im all for different ideas that work.....Keep the ideas coming i say!!!
Thanks everyone...WM
ps edited because of spelling mistakes....sorry |
| gholt |
Posted - 01/04/2008 : 05:39:58
WindyMiller,
I like your use of the air dams and especially the balancing concept - outstanding.
As long as we're looking at "out-there" designs ...
6000 watts at 32.5 mph when corrected for sea level.
Full size images and story here:
http://www.speakerfactory.net/wind_old.htm
G. |
| MattM |
Posted - 01/04/2008 : 04:50:17
I've always wanted to do a planetary shaft that drove counter-rotating blades, only one blade smaller diameter tied to a blade that really only caught wind past the perimeter of the smaller blade. By tying the two together the smaller blade could be actually driven at a ratio where the blade tips are roughly equal in tangential velocity.
Go Huskers! |
| BushWhacker |
Posted - 01/04/2008 : 04:34:46
Pretty wild and 'out there' stuff you are building Windy. Excellent!
Everything should be made as simple as possible, but not one bit simpler. - Albert Einstein |
| gotwind |
Posted - 31/03/2008 : 20:42:31
Hi Windy.
Agreed, video never gives true speed of blades - shame really.
I appreciate your blade design is meant for a HAWT, I wonder how it would work as a VAWT? - might be worth a try - I don't know.
Ben. |
| windymiller |
Posted - 31/03/2008 : 20:33:23
Thanks gholt for your advice.
Im in full agreement with the idea of making the steel bar arms more streamlinedin some way.
The aerofoil cross section in the forum topic you mentioned is very similar......the only difference i can spot is that my blade has a more concave shape on the blade face which at the moment does give good performance.
It could be quite possible im sure that other profiles may work better than the one im using?. im not sure.
Please dont forget that this is a HAWT not a VAWT.....the picture is misleading with it laying down like a VAWT...i wanted to get a good photo, so i dismantled it,then took the photo.
In reply to kr2bldr about a video clip...i most probably will in the near future.
The only downside with video clips is they dont give a true representation of blade speed when theyre going above a given speed.
Shame really because it really does perform beyond belief.
Thanks everyone for the replies...appreciated WM |
| gholt |
Posted - 31/03/2008 : 19:28:11
Hello windymiller,
The working portion of your blades is at the correct end. The blade efficiency can be increased by utilizing the outer 2/3s of the blade radius with your airfoil profile. The noise level can be reduced by adding fairings to the other portion of your blades. There's a fine example here:
http://chrusion.com/BJ7/Streamline/fairings.html which is a very nicely done version of an airfoil, not dissimilar to what chris_psmith is attempting.
http://gotwind.forumco.com/topic~TOPIC_ID~568.asp
The down and dirty method would be to wrap aluminum flashing (roof flashing) around the "arms" in a symetric airfoil shape and using pop-rivets to close the trailing edge.
Garland
|
| windymiller |
Posted - 31/03/2008 : 07:31:51
The blade design is for a HAWT.
Pitch can be altered by loosening the nylock nuts at the ends...setting pitch required,then retightening.(setting pitch is very important for speed)
Balancing the blades are easier,as you can move blades inward towards the centre using the threaded bar ends.
Once going it really does let rip.
Ive had it mounted on a steel pole around 10 feet from the ground on a reasonably windy day and it really does go some.
It all depends how much "bottle" you've got before you turn it away from the wind.
People who have watched it work for the first time LOL when it starts going....then run off when they realize its just going faster and faster and start making funny noises (like three musketeers having a sword fight!!! whip whip whip )
Hand on heart it does do as ive described.......it really is dangerous to use on a turbine ,so think TWICE ...i cant be held responsible for what you may construct.
Have fun....WM
PS....im thinking of makind a four bladed version,with the inner two paddles slightly shorter so as not to interupt the wind flow of the outer blades....should be interesting!!!!! |
| MattM |
Posted - 31/03/2008 : 04:43:17
Is this for a vawt or hawt?
Go Huskers! |
| kr2bldr |
Posted - 31/03/2008 : 01:34:17
neat! I would like to see some video of it.
Keith and Martha Crawford
Lansing MI
martha.simerson.net |
