Author Topic: My VAWT Project (Read 6132 times)

wind4Reg · « **on:** May 29, 2006, 03:50:46 PM »

Well I decided to actually build the monster, a straight bladed H-Rotor VAWT with 12 foot blades and an 18 foot diameter. I have started with the blades first and have a huge amount of glueing to do.

Here is a pic of the pile of lumber I am using to build the blades:

This pile of lumber is 39 spruce 2"x6"x12' that has been halved to create 78 2"x3"x12' pieces. The idea is to laminate 13 of these pieces together which will eventually form half a blade. This will be done 6 times to create 3 blades. I am initially building 3 blades for this turbine, however I plan to build my hub so that I can use either a 2 or 3 blade format. If the performance from a three blade configuration is poor then I can use the two blade configuration that worked well with my 3'x5' model. I expect I will be glueing these together until mid summer before I can actually start shaping these into blades, since I only have the one glueing jig (12" I-beam).

Here is a pic of the jig:

I will have to glue 72 times just to create the laminated half blade pieces. I have been at it now for a couple of weeks and it has become my daily religious ceremony to the wind gods, I must perform the glue ritual each day ;-)

Here are the wooden dowels that will be used to strengthen the laminated half blades:

Here is my template with 80 stations that will be used to shape the blades:

I will add to this build diary as progress continues, since I will be mainly glueing for some time, it will be a while before there is any major progress. I am thinking strongly about modifying my glue jig so that I can stack and glue more pieces at a time.

I will update this diary with more pics and info as progress continues.

wind4Reg

Jon Miller · « **Reply #1 on:** May 29, 2006, 05:26:05 PM »

Thats gonna be a big VAWT, what hub are you planing to use, also what sort of power are you hoping for?

whish you the best of luck it sure will be impressive

rotornuts · « **Reply #2 on:** May 29, 2006, 10:16:38 PM »

looks to me like someone is having alot of fun.

Mike

wind4Reg · « **Reply #3 on:** May 30, 2006, 05:54:31 AM »

This size of a VAWT would be rated at 7kw @ 10m/s with a normal average operating rating of 1.5kw-2kw. Depending on the overall efficiency of the system, I would like to be in the 2kw range under normal operating conditions. I am planning to use a heavy duty 4x4 truck front hub plus use an additional stablizer bearing on the main shaft to help distribute the forces the main hub will encounter. Attached to this truck hub will be a custom built swappable arm attachment piece so that I can run with 2 or 3 blade configuration.

wind4Reg

electrondady1 · « **Reply #4 on:** May 30, 2006, 11:07:55 AM »

will you get enough rpm to go direct drive on the rotors?

wind4Reg · « **Reply #5 on:** May 30, 2006, 12:06:39 PM »

I am planning on having the gennie at the base of the tower, powered via a shaft and if necessary a gearbox. So this is probably different than what you were imagining. I will have to match the gennie to the rotor after I try it to see what the avg RPM is. I have looked around an I haven't come across a way to determine the rotor speed for a given windspeed for a VAWT. If you know of a calculation for VAWTs that will tell me that, please send it to me.

thx,

wind4Reg

vawtman · « **Reply #6 on:** May 30, 2006, 02:01:06 PM »

Those should be some tough blades Reg good idea.Goob luck and cant wait to see futher updates.

WXYZCIENCE · « **Reply #7 on:** May 30, 2006, 04:21:10 PM »

wind4Reg, Very interesting. What do you estimate the total weight will be for this monster? What kind of thrust bearing are you going to use? What is the little foil shaped thingy on the wood stack? Joe.

zapmk · « **Reply #8 on:** May 31, 2006, 06:33:00 AM »

Wind4Reg,

Heres one that I found that was posted by windstuff Ed awhile back.

Wind Speed x 88 / ( diameter x 3.1415 ) x Tsr = rpm

-Zap

electrondady1 · « **Reply #9 on:** May 31, 2006, 06:40:22 AM »

reg, it's good you can keep your options open in regards to the geni. since it will get lift from the profile it should turn quickly but with such a large dia. it should rotate more slowly . the end result, speed and torque !! good luck, the wind gods are waiting.

wind4Reg · « **Reply #10 on:** May 31, 2006, 11:38:37 AM »

Thanks, now I just need the TSR calculation for a VAWT blade to plug that into the formula. I think this is where I got to before and wasn't able to find a formula for TSR. Can you help with that one?

thx,

wind4Reg

wind4Reg · « **Reply #11 on:** May 31, 2006, 12:07:06 PM »

The total weight is HEAVY ;-)

Spruce is 450kg/cubic meter, and each blade will have a steel spar in it as well, given a volume of each blade is approximately 0.0945 cubic meters with the material removed for the steel spar, plus the weight of the steel spar, each blade will weigh about 93.4 kg or 205.5 lbs. Multiply that by 3 for all the blades and you are looking at 616.5 lbs, then we add on the weight of the crossarms and hub, approximately another 275 lbs, so the complete turbine will weigh approximately 900 lbs. My estimates for the tower weight is approximately 2500 lbs, so the total weight, so if you add in the generator and the turbine you are looking at over 3500 lbs, or about 2 tonnes. :-D Yep, HEAVY. I have not made a final decision on the main bearing yet. The foil shaped thing on the wood stack is one that I cut out of of wood and it is the same size as my profile except much shorter of course. It just helps me visualize what these blades will look like, so I keep it around, it's a helpful motivator.

wind4Reg

wind4Reg · « **Reply #12 on:** May 31, 2006, 12:28:07 PM »

I got a few more clamps and modified my clamping jig by welding some uprights to it so I can glue and stack now and do 3 days worth of glueing in one day. Thats much better, I couldn't imagine glueing everyday for 3 months, but I can handle 1 month of glueing.

Here is a pic of the updated jig:

thats all for now,

wind4Reg

zapmk · « **Reply #13 on:** May 31, 2006, 12:54:19 PM »

wind4reg,

Heres Ed's formula for finding TSR.

Rotor RPM /(Windspeed MPH X 88 / 25.13) = TSR

-Zap

wind4Reg · « **Reply #14 on:** May 31, 2006, 02:19:17 PM »

Thanks Zap, we are getting there, now the Rotor RPM is required, and the only way for me to know that is to build it and see what the RPM is at a given windspeed, unless you know of another formula to determine the rotor RPM without using the TSR, if so please send it along and then I can run the numbers.

wind4Reg

vawtman · « **Reply #15 on:** May 31, 2006, 02:50:12 PM »

Reg all I know is that has you increase the diameter vs height things slow down,tested that.The actual speed will probably be dependant on your design.

I thought about building a adjustable rotor sorta like farm wagon poles have to set the blades at different widths for different wind speeds.Hope I helped a little.

zapmk · « **Reply #16 on:** May 31, 2006, 03:19:02 PM »

Wind4reg,

It's all going to be base on now much lift your air foils

will produce. So the only way to find TSR that I can think of

is to put them in to service, and see how many rpm's it will turn

at a given wind speed.

To kind of get an idea of RPM's, you could take some of the TSr information

found from the other posters machines.

Vawtmans I beleve came out to a TSr of 1.4 using air foils.

So using his TSr your machine could turn.

wind speed of 12 mhp X 88 / (18 foot X 3.1415) X 1.4 = 26 Rpm

Base on Ed's Drag/lift ( lenz2 ) machine TSr of .8

windspeed of 12 mhp X 88 / (18 foot X 3.1415) X .8 = 14.9 Rpm

It going to be a very slow turning machine.

Hopefully somebody can correct me if am wrong. Ed- Vawtman ?

-Zap

wind4Reg · « **Reply #17 on:** June 01, 2006, 05:40:04 AM »

Hi Zap, yah I think your right, the only way to know for sure is to try it. I am hoping to do a little better than Vawtmans TSR of 1.4 since I am using symetrical blades instead of cambered and since this is a lift machine I should be able to do much better than the Lenz2 machine. From actual university mechanical engineering experiments conducted on the same VAWT with the same length, chord and number of blades fixed at 90 degrees to the crossarm, the symetrical ones (NACA0018) outperformed the cambered ones (NACA4415) to everyone's surprise since everyone thought the cambered blades were superior until tested. So my target TSR is 2.5 - 3, but we will see what I am actually able to get.

wind4Reg

vawtman · « **Reply #18 on:** June 01, 2006, 03:44:55 PM »

Hello Zap

I think your figures are pretty close for this machine.

Their are a couple bugaboos that might sneak into the equation I think.

The drag created by the use of truck axle would hamper startup and overall speed.Not including the gen.
On my 8x8 the slightest drag at startup the blades have start problems but if I let them freewheel(only 2 small bearings) and connect the 5hp conversion to it a 15mph wind the blade speed seems unaffected and the small elements hooked up to it got pretty warm only gearing 3;1 will need to increase that ratio.

I am a beleiver that has the diameter doubles the number of airfoils should double also.I dont know why and havent started on the big unit yet.

Things arent easy but FUN.

vawtman · « **Reply #19 on:** June 01, 2006, 04:19:13 PM »

oh and forgot to add that Eds machine might be slower but being half sav could overcome the initial drag.

wind4Reg · « **Reply #20 on:** June 02, 2006, 06:12:56 AM »

Hi vawtman, can you tell me what you mean by:

The drag created by the use of truck axle would hamper startup and overall speed.

Are you talking about using the rear axle of a truck? I was planning on using the front hub and axle off of a 4x4 truck.

Also are you saying that if you built a 16' machine that you would go with 4 blades instead of 2? I am interested in what has lead you to believe this, if this is what you meant.

I have been thinking about your point #2 for self starting as well. I know that with my 3x5 model when I hooked up the chain drive and the generator, it didn't self start in low winds like it did before when it was free spinning with only the bearing's resistance. However once the wind picked up a bit it did start on it's own and once it got going it was running pretty fast with the added drag of a sloppy chain drive. So I know what you mean by the startup drag. I was thinking that a centrifugal clutch might be useful to help with this issue.

wind4Reg

SmoggyTurnip · « **Reply #21 on:** June 02, 2006, 06:59:36 AM »

Why can't you glue the whole thing at once?

.

vawtman · « **Reply #22 on:** June 02, 2006, 08:46:13 AM »

Your hub idea is a good idea I misread that.

sorry.

The additional blades I think would help large diameter turbines.I just have a gut feeling on that.

What im working on now is a small savtype turbine mounted below with the gen hinged so has the wind pushes against it would engage the gen while the turbine is allowed to freewheel during calm periods.Could you get a clutch to operate at the rpms were talking here?If you know a way let me know.Thanks

elvin1949 · « **Reply #23 on:** June 03, 2006, 06:47:50 AM »

Vawtman

Weaker springs will lower cutin speed on clutch.

I don't know how low you can go.Will have to

experiment to see.

later

elvin

wind4Reg · « **Reply #24 on:** June 03, 2006, 08:50:21 AM »

Hi poster "formerly known as vawtman" ;-) The clutch would have to be placed on the output of the gearbox which would mean that it is on the fast shaft just before going to the genny. With weaker springs you should be able to have it work in the 500 - 1000 rpm range. Playing with it a bit would help you set the correct "engage" speed.

Just my thoughts,

wind4Reg

wind4Reg · « **Reply #25 on:** June 03, 2006, 09:00:57 AM »

I am glueing 2 and sometimes 3 pieces together at a time for a couple of reasons. First is my limited tool supply. I have a short 7/16" drill bit that will only go through a maximum of 3 thick when drilling holes for the wooden dowels that are going to glued through each half blade. The next tool problem is my thickness planer only will plane up to 12" wide pieces, so I can't glue together too many at once. Then my jig will only allow me to glue together a maximum of 7 pieces at once. I also think that glueing them in 2 and 3 pieces at a time helps straightnen the pieces. Some have had some warpage and glueing them this way seems to help with that too. Now if you are wondering why I am building half blades as opposed to just glueing together the 2x6's to start with and carving out the blade shape, it is because I am putting in a steel spar. If you look at the template pic above you will notice a notch mark in it on the straight side. This notch will run down the length of the blade and allow me to put in my steel spar.

I hope that that answers your questions as to why I might take this seemingly strange approach to building blades.

wind4Reg

wind4Reg · « **Reply #26 on:** June 22, 2006, 07:07:51 AM »

Here is a picture of me holding the 12' long laminated section of 13 pieces. This piece will eventually be half a blade. I am slumped over and my knees are buckling under the weight of this blade section. Hurry up and snap the picture already! It weighs around 200lbs so it was a pretty good lift. A little more gluing (only 5 days of it left, hooray!) and then on to the thickness plane phase.

wind4Reg · « **Reply #27 on:** June 27, 2006, 08:05:37 AM »

At last the second gluing phase has wrapped up. I took a few pics of the last quarter piece being laminated.

First I coated the dowels in glue:

Then I hammered them into the piece on the jig:

Then I brushed the glue on the already laminated 2 piece:

Then I joined the two pieces together:

This process was repeated for the next piece of 2 laminated wood. Then the unit was clamped to the jig. Finally, the last quarter to be laminated. I now have 12 laminated quarter pieces, six of 6 pieces laminated together, and six of 7 pieces laminated together. The next phase is the planing phase. Unfortunately the planer is in need of repairs and I have to wait until the parts come in for it.

As soon as it is up and running, I'll post some pics of the planing process.

bparks · « **Reply #28 on:** June 27, 2006, 11:24:03 AM »

That is really looking great! Have you thought about adding support at the perimeter? I think you could dig a circular trench the same diameter as your mill, and pour a concrete track. Then some sort of wheel mounted under each blade could ride the track & take a ton of weight off the hub. It would add some drag & noise but might be worth considering.

vawtman · « **Reply #29 on:** June 27, 2006, 04:52:51 PM »

Reg i must say you are a workhorse.And your turbine will reward your efforts.Carry on

wind4Reg · « **Reply #30 on:** June 28, 2006, 05:59:00 AM »

Hi bparks, I am going 80' in the air with this one, and I am planning on using a hub from industrial equipment now. The hub has built in planetary gears so I will get an immediate speed increase to the output shaft.

XXLRay · « **Reply #31 on:** April 11, 2010, 01:49:38 PM »

As this topic has not been updated for a long time - is there any progress?

News:

Author Topic: My VAWT Project (Read 6132 times)