Introduction: Savonius Horizontal Axis Wind Turbine
This Savonius horizontal axis wind turbine (SHAWT) is an ongoing project that I'm still evaluating and modifying according to whatever observations are made during the testing. The opening photo shows the SHAWT as it is right now - testing will continue over the winter months.
I just finished putting together the most important video to date on the turbine (see Step One below). Earlier I made a video that covers the theory of the idea. This video discusses the theory of the SHAWT turbine
If you look at the current video (Step One) after you check out my theory video you will see that my theory on how the turbine will perform is completely wrong especially as it applies to controlling over speeding. More on that later. But the good thing is that we end up with a turbine configuration that is very effective in keeping the turbine from self destructing in high winds.
Step 1: Video on Fixing the Tail Wagging and Testing the Turbine in the Pickup Truck
I'm in Canada and our speedometers are calibrated in kilometers per hour. I set the wind speed anemometer to km/h to help me relate easily to the speed limits while driving with the turbine mounted on the truck. In the spreadsheet I selected 50 km/h to show how the turbine is performing in different configurations. 50 km/h is equal to about 31 miles per hour.
I realize that this is a long video so if you want to quickly check out the analysis section (spreadsheet) you can jump to 9:55 mins in the video.
Step 2: Fabricating the Turbine (Part 1)
I made the four Savonius "buckets" from two stainless steel buckets that I bought at Princess Auto. They were about $20 each. I cut the buckets in two using my angle grinder. Because I wanted a machine that would last long enough to do some extensive testing I went with 1/2 inch pressure treated plywood for the bucket bases. The U-shaped turbine frame was made from pressure treated 2x6's. My original thought was to use cast iron plumbing flanges to secure the buckets to the turbine shaft. Turned out the flange hole diameter was a little too large to give a good aligned fit so I ended up buying inexpensive 1 inch collars and large steel washers to do the job. I welded the washers to the collars and drilled holes in the washers to attach the assembly to the plywood bases. The turbine shaft is 1 inch O.D. aluminum pipe. The collars slide very snugly on the pipe and I secured them with the setscrews that came with the collars. (I also bought the pipe, collars and washers from Princess Auto).
Took three tries to get the tail pieces large enough to get rid of the "tail wagging the turbine" that you will notice in the video. In reality the wagging was most likely due to the power plate buffeting in the wind.
Step 3: Fabricating the Turbine Part 2 (this Step Includes a Video That Covers Fabricating and the 1st Road Test)
After the tail wagging the turbine problem was fixed I set up a means of locking both the turbine yawing and the tail/power plate tilt angle in place. This made it easy to run the turbine on the pickup without having to wonder what the configuration of the power plate and yaw was at any particular time. The system worked very well as you can observe in the videos.
Data collection was a bit of a challenge but the use of cameras to record what was taking place worked out ok. It was a bit time consuming to get the data collected and recorded but in the long run, as you can see on the spreadsheet, it all worked out in the end.
Step 4: On Going Testing With the Turbine Fixed on Land
I now have the turbine erected on dry land ready to take advantage of our winter winds. I've installed gas springs to control tilting of the tail and therefor the location of the power plate. The tilt back is limited to 50% so that, if the observations up to now are valid, we should have real good overspeed control. Ideally I would like to see a wind speed of about 160 km/h (100 mph) to give the turbine a good survivability test.
I will update the instructable as time goes on.
Step 5: Update... Nice High Winds Gave the Turbine a Good Workout Yesterday
Step 6: The SHAWT Survived the Winter!
Although efficiency, noise level, appearance, etc. are important for wind turbines, survivability in extreme weather conditions is the ultimate indication of the practicality of a machine. The SHAWT came through the winter with almost flying colours. The two inexpensive gas springs failed after getting beaten up over and over with some high winds. So then I need to find better quality springs or at least springs that are intended for exterior use to continue with long term testing.
This video is long and is really "for the record" account of the turbine performance over the past winter.