So I am taking the plunge!
I decided on a VAWT design mainly due to the ease of design and build and the fact that I could easily do it with some limited materials I had lying around. Now that I have acually built a test rotor, I am quite surprised at how well it works in light winds (all I have had to test it in so far). So, I am pretty confident about the final product as a small scale turbine. It could however be scaled up a little but lets first see how this one goes. I thought I would just post a little info to let people know what I am doing and try and get some input/advice and comment. So, here goes.
I have gone with a Savonius design I found online. It is based on the following basic design
This is supposed to be more efficient than a regular drag design for 2 reasons. Firstly, the wind coming in the one side is channeled through the center to the other side and expelled, creating some extra force on the opposite end. Secondly, the curved surfaces act like an aerofoil and are supposed to create some lift, which also helps spin the rotor. If these 2 parameters actually make any difference, I don't know, but I liked the design anyways. Here is a pic of my turbine from the top.
I essentially just printed out a template and then cut out 2 pieces of wood in that shape. I then use screws to attache a sheet of aluminium flashing to either side to create the actual rotor surface. The flashing was 50cm x 60cm. The following pic shows a slightly better angle to hopefully give a better idea of what the rotor looks like.
Just in case anyone is wondering, that thing attached to the top is a bicycle front wheel hub, which I plan on using as my bearing. Was the cheapest (R22) and easiest thing I could find that is designed for high loads. Should work ... I hope
I have also created a small (2mb) video clip so you can see it in action. The hub isnt attached to anything yet so I just held it between 2 pieces of wood and opened my front and back door to create a bit of draft. It spins quite freely in only very little wind. The video can be downloaded from: http://users.iafrica.com/e/en/enervate/wind/Movie.wmv <--- (just copy and paste into your browser and you should be able to download it)
I will use the frame that can be seen in the movie to mount the whole turbine in once it is done. It is an old steel fish tank stand so should be pretty stable. Next bit is to find or make a generator. I would really like to make one but magnets are a little pricey and not so easy to come by so I will see what I can find in terms of an old motor.
I can get 50x20x8mm N37 Neodymium magnets but they may not be strong enough as they are so thin. They are kinda cheap at R30 each (R100 for shipping 12). So I might do it and make a generator with 2 rotors, one on either side of the stator, which should maximise the magnetic field. I will see what I can scrounge up this weekend though as I have a few potential opportunities in terms of motors.
I hope you enjoy what I have done and PLEASE COMMENT!!! Let's generate some discussion around this