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Forum Index : Windmills : VAWT --- Amin, Sr Members, Actual Users
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| Solar Junkie Newbie  Joined: 03/05/2009 Location: United StatesPosts: 5 |
First post. What I am trying to ascertain: Question #1: What VAWT design (Savanious, Lenz2, Giromil, etc) would best meet the RPM and PMG figures listed below? Question #2: What is more enduring (VAWT, HAWT, etc) in windy area with what I would deem extreme conditions (more about that below)? RPM range desired: * ~50-rpm at roughly 4-mps * ~180-rpm at roughly 13-mps * ~220-rpm at 20-mps or greater This is what I know about this particular PMG I'd like to purchase: * Low cogging and resistive torque design * Gearless, direct drive * Rotor inertia (Kg.m2): 0.066 * Starting torque: < 2.0NM * Phase resistance: 2.7ohms My Winds: * Dry thin air at about 2,700 meters above sea level * Usually no greater than a 30 degree variation from one direction during a storm or during the normal course of the day * Usually from the south all year long More detail: I have read a bit hear and elsewhere about DIY VAWTs. My eyes have glazed over and my bum is numb from sitting here days on end.  I am still a bit dumbfounded and am looking to those here that have actually built or used a few of these VAWTs. I just can't justify spending the BIG bucks on a commercial VAWT or even a variable pitch HAWT unit. The return on investment seems very low. I think I have access to a plasma cutter if that helps.... I know I have access to a good welder (brother-in-law).
Again, I am most interested in something that will spin between 50 and 180-rpm in normal conditions and not more than 220 rpm in storm gust winds. About my location: My off-grid cabin/house is located on flat steppe land at 2,700 meters above sea level between two mountains that are a bit higher (some peaks are about 4,100 meter); thus, thin dry air. It can be very windy here and has destroyed many small HAWTs... in particular my 400w number that came with the place  From my casual observations over the last year via my Air-X turbine I can say that the winds are generally in the same direction most of the year. During a storm the vary little in their direction (30 degree variation max) and the gusts behave the same. I am very reluctant to purchase another Air-X or anything else that company makes   ..... so here I am trying to learn 
The average yearly wind is around 5mps, but during the more aggressive storms it can be a steady 18mps and gust upwards of 25 to 40mps. Normal storms seem to drive the winds at 10mps with gusts around 15mps. I heard that one storm a few years ago produced 53mps gusts (I did not live here then). I appreciate your comments and suggestions! Silly remarks are just as welcome <g> Sorry about it being so long winded..... Solar Junkie  |
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| Janne Senior Member  Joined: 20/06/2008 Location: FinlandPosts: 121 |
If you really want to get good power from the wind, then HAWT is definitely the way to go. hint: available power from the turbine is directly proportional to the turbine swept area. If at first you don't succeed, try again. My projects |
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vasi Guru  Joined: 23/03/2007 Location: RomaniaPosts: 1697 |
A good VAWT can do (some how) what solar panels can do. Suporting your HAWT, maintaining your battery bank. An Air-X is good on strong winds and storms. This and this are good choices as VAWT's Or, you can choose a middle way. A HAWT with these unexpected good performing blades or a HAWT with 5 or 6 blades. Both types are strong enough in storms if you adjust the tower "length/strength" according to your wind conditions and turbine weight. Well, it's sound as adevrtising but is what I believe. Hobbit name: Togo Toadfoot of Frogmorton Elvish name: Mablung Miriel Beyound Arduino Lang |
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| Solar Junkie Newbie Joined: 03/05/2009 Location: United StatesPosts: 5 |
Thanks for the quick replies. HAWT still intrigues me, but commercial companies like SWWP and their Whisper 100, 200 & 500 models have been torn up around here. The only HAWT that seems to last for any length of time around here is their 400w Air-X model..... and the one that came with the house failed. Maybe it was installed wrong??? Even at that customer support from that company was... well, to put it nicely... sucked. The only HAWT that seemed to tickle my fancy and my pocketbook were a few Kestrel products. But.....I hate to spend the money on a variable pitch Kestrel knowing per their wind chart/diagram that I would have to refurb all moving parts about every five years (basically everything expensive).... funny... their distributor never followed up on the associated costs of the refurb....or warranty questions. The cml VAWTs seem pricey as well for anything with any umph... & I know basically nothing about them. So I figured I'd build something on my own to learn and maybe get a bigger bang for the buck. Although the other big obstacle seems to be regulating/stabilizing the voltage down to 24v. Saw a Chinese VR that could drop 400v down to 48v.... but I am weary of the reliability factor and I would have to finger out how to drop it further to 24v. Hate to have the house burn down. 
I'm starting to dig into more posts and also re-reading others. Somehow I missed the RPM equation that the Lenz2 turbine had for it.....Excerpt: How fast will it run in a given wind speed... Windspeed x 88 / ( diameter x 3.14 ) x TSR So I guess I need to start over, re-read everything and look up TSR values for Savanious, Lenz2, Giromil, etc. Any one have TSR values handy for those different VAWT designs? Thanks again, Solar Junkie |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Solar Junkie, how many do you think of the systems that have failed in your area were actually due to failure of the supporting structure? |
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| Solar Junkie Newbie Joined: 03/05/2009 Location: United StatesPosts: 5 |
All the reports I've received back have been blade failures. No tower failures that I know of. My GF's co-worker stop selling and installing turbines. He only does solar now (side business). The other store in town is shy about them as well. I recall him saying that in our neck of the woods that the big blades break well before the little ones do in reference to SWWP products. I know of no VAWTs in my area...???? I think my HAWT situation was a blade failure. One bolt was missing. I assume it vibrated loose. The other snapped off and a portion of it was still in the hub. Now... the one that was missing may have snapped clean off. The graphite blade was missing almost an inch (2.5 cm) from the tip, but was as stiff as the other blades upon inspection. I did not notice any strike marks on the tower attached to the barn, but it was blowing enough that night to shudder the log house a couple times. Those Air-X turbines spin at about 1,600 rpm at their rated power. I'm guessing it hit the pole.... but I don't know if it was before or after the bolt went....? The nose cone was in pieces on the ground. The pole made out like a champ.... still standing strong. The barn had no marks, etc. Fortunately none of the critters or any of us got speared. Cheers, Solar Junkie |
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GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Solar junkie, My avatar says I am a Sr Member, so I must be. The problems with typical windmill failure is the windmill design, commercial, or amateur alike. Usually too greedy with the power production. Any windmill that does not furl, or present a reduced profile to extreme weather will likely fail before the tower does. My windmills I have designed are conservatively rated. I do not attempt to extract every bit of power from the full spectrum of winds that I get at my site. My windmills endure 100kph+ winds several times a year. In any winds above 40kph, my windmills are close to fully furled and only attain a max of around 400rpm. I have also seen many broken commercial units, including burnt out systems. The commercial units have usually cast furling pivot components, so mods to furling are limited to reducing tail weight and posssibly length. Any windmill can be made to survive any weather at the expense of upper power output levels. Once the novelty of the quoting of maximum power output levels has worn off, it is time to make the windmill an item that has long term survivability. Too many people blame the weather for breaking their windmill, but less would be broken if they were designed to let the extreme wind just pass by. The extreme winds may only occur a few total hours a year, and it is unlikely that not allowing the windmill to harness the energy will reduce the accumulated power output by that much. No point in dumping power to a heater bank if the windmill breaks doing it. Stories of windmills breaking in storms only harms the industry. Having the windmills survive the elements and wild weather is what the designers should be looking at. My two bobs worth. Gordon. become more energy aware |
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| Greg Hudson Newbie Joined: 28/04/2009 Location: AustraliaPosts: 22 |
Want to see a large WT explode ? Check this out... http://www.youtube.com/watch?v=CqEccgR0q-o Regards, Greg. |
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| petanque don Senior Member Joined: 02/08/2006 Location: AustraliaPosts: 212 |
Is part of this a maintenance issues? The nature of wind turbines is that they can’t be set and forget like solar systems. After all if you drove a car 5 to 20 hours a day and never did any maintenance to it is it realistic to expect 20 or more years of service from it? |
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| Solar Junkie Newbie Joined: 03/05/2009 Location: United StatesPosts: 5 |
GWatPE..... I agree 100%. Marketing and short term profits are being chased at the cost of quality. petanque don.... I was the proud owner of this baby for only several months. I was just about to go up and check the lil' booger when it blew up. I was working on/finishing the house in the attempt to beat a refi deadline or I would have done it sooner. Made the deadline and lost the turbine... oh well. Either way, I believe it was only 3 years old. I agree that maintaining a geni makes total sense. |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
I've been building windmills since I was a teenager. I'm 60 now. Here are a couple things to consider: HAWT designs take advantage of "apparent air" similar to the jib sail on a sailboat. The forward movement from momentum collects and uses more air than can be utilized in a static condition. VAWT designs are basically paddle wheels in the stream of air. They can be large scoops as a Savonias or designed as a Darius, which needs to be manually started until its speed nearly matches the wind flow. VAWTs are nice, because you can put all the "machinery" at ground level and don't have to bother with orientation gear (tail). In general, HAWTs are about 8 times faster than VAWTs and I prefer them over the vertical designs. A HAWT grabs more raw power per revolution than a same-sized VAWT. You also have to decide if you want to generate your power directly from the activity of the turbine or if you'd like the turbine to create energy that can be stored and used later. All my designs for the last 30 years have been small air pumps on HAWTs and I store the air to use in an air engine down on the ground in my shop. I've built several VAWTs and enjoy being able to walk up and work on the pumps, which run from a "swash plate" attached to the central axis, but I still prefer the HAWT design for overall performance, reliability and maintenance. One major drawback is birds; they get whacked now and then in my little HAWTs, but a VAWT turns slower and is more visible to them. I utilize a swash-plate design as an easy method of changing rotary to linear motion because my air pumps are all double-acting push-pull designs. Hope that helps you in your decision making. Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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oztules Guru Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
SolarJunkie. If your living off grid, then you need reliable power. To save diesel, you need a fair bit of it and regularly. A Vawt is good for lots of interesting things, but producing decent quantities of power is not one of them. The PMA with the 2.7ohms phase resistance is a toy device... unless it is high voltage, and then it will need to be have a high pole count to be useful.... as you will most likely need a transformer. What voltage are you talking about.... at 12v You can work out the current that can flow in those coils with this formula Amps=voltage/resistance..... at 12 volts over 2.7ohms.....that don't look good for an off grid dwelling. At 24v it's not too flash, at 48v it is still in toy territory for off grid applications. Air-X are not really my idea of a decent windmill from almost any perspective, and are not suitable for off-grid applications. They maybe alright for a holiday shack, but not a dwelling.... too noisy, and don't produce enough power consistently. To get good consistent power you need cross section swept area.... up a high pole. Vawts are very clumsy at this, hawts can describe a large swept area with very little rotating mass for a large blade. Vawts are cumbersome when you start to get decent swept area, and the thought of it up a decent pole is frighting. Mills at ground level are ornaments. If you must go for a commercial design, I would err on the side of the AWP... but not the African version (very poor manufacture of a very good robust design) There is an American version getting around, and it is that style of heavy robust machine I would go with if I were off grid and not building it myself. Get the furling correct, and the machine will do fine in all conditions. (What Gordon was getting at) ..........oztules Village idiot...or... just another hack out of his depth |
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