When I took the video yesterday, Sunday, May 12, the wind just started picking up. It got much more stormy over the night, which I could not film because of darkness. It's still really ugly and windy outside. We are lucky here, as it's not really bad, but other areas really get blown to bits. This type of weather has been going on more or less since early March, with a few small breaks in between. It's been like that for most of Europe. The alps continue the get heavy snowfall and the temperatures are so much lower than they should be, yet the weather people on TV call it one of the warmest springs? Wut? Maybe in another dimension.
The wind was variable, but we had a gust here and there. The VAWT was able to turn but did not perform as hoped. I think the pivot point was to far from the center of pressure, it wasn't balanced carefully, and one pivot seemed to hang up. So I suppose I'll have to make another only put a little more care into the construction.
Details from the construction of a small Sharp style vertical axis wind turbine. There is a little video of it trying to spin, but the wind was so light and variable it really didn't get going. I was happy it turned at all considering the size of the wings compared to the diameter.
Shot on location at Barnsdall Park on Hollywood Blvd. in Los Angeles, CA.
Music by William Schaeffer. Performed on Casio Privia Px-150
The feathers and necklaces were found objects. The feathers seemed to have a perfect balance of weight and wind drag between the right and left. While I drove they seemed to flutter and fly through the air.
Details of the construction of a 0.10 m^2 horizontal wind turbine using 3-D printed airfoils and mostly PVC pipe and fittings. A rotor with magnets was constructed using a Blue Diamond Almonds nut can, and the stator was made using a 3-D printed bobbin and wound with 26 turns of 26 AWG magnet wire.
I tried making a vertical axis wind turbine with a lower solidity because I wanted to see one operate with a fairly high tip speed ratio. I knew going in that it would not start on its own, and it certainly did that. I could not get it to start at all. Possibly because we did not have very good wind for weeks. Perhaps I did not get it spinning fast enough to keep the wings from stalling. In any event, it looks like this experiment was a flop. But I posted the video for documentation sake.
A brief characterization of the VAWT generator and estimation of tip speed ratio (TSR) with some clips of it spinning in the wind. I don't have power production data. Our wind resource is quite poor, and we might not have enough wind to collect power data for some time. The TSR is in the neighborhood of 1.2 to 1.4; a bit low for a VAWT, but not unexpected for a small turbine with relatively large wing chord.
A brief look at a small Savonius vertical axis wind turbine made from Coroplast material and attached to a generator described in previous videos. No data is presented as we had no wind to speak of for over a week and I wanted to move on to another turbine idea.
I tried making a wind turbine to go with a small DC motor. My 3D printer is small so I'm limited to parts that are about 4" in diameter. A Savonius rotor of that size was not enough to overcome the drag from the motor. So I tried making an experimental VAWT. The connection between that VAWT and the motor was too weak, but when placed on a simple dowel axle, it would spin well in a good breeze.
A followup video about the VAWT035 project. This is a look at how the various components have fared after a couple years of use. I'm quite happy with how it held up. The tops of two of the blades were eroded; possibly due to woodpeckers. However, I took down the windmill because I use a solar panel now to keep a battery topped off and the pole is now gone because I got tired of mowing around it. Our location is not very suitable for wind power and I am not planning on pursuing the project any further.
In an effort to improve its performance, the wings of the Foam VAWT were made stiffer by adding some glass fiber packing tape along with a coating of clear packing tape. It did better than the foam wings by themselves.
We finally had enough wind to test the LM2596 controller. I wanted to highlight two improvements over the MC34063 controller. This controller limits the current on a cycle-by-cycle basis so I believe the current reading on the Watts-Up meter is closer to reality. The previous controller used a low frequency PWM signal to turn it full-on and full-off. So when it was on, the controller was hitting its current limits while the capacitors discharged. The Watts-Up meter would pick up on the current peaks and display a false peak current. The second improvement is in the software. As the input voltage nears the point where it will trip the SCR, the controller starts calling for higher levels of current (a more aggressive current vs. RPM curve) in order to slow the turbine and delay shutting it down with the SCR. This video is the last in my series on the 0.35 m^2 vertical axis wind turbine. My hope was to be able to produce them for a reasonable price. But I don't think it would be worthwhile to make and sell them for less than $800, and there did not appear to be a market. I gave this one away and have since moved on to other projects and turbines. (9/16/18)
We had a fairly windy day, so it was a good time to test the over-voltage circuitry. A 36 volt zener diode connects to the gate of an SCR. This is just a demonstration of the circuit function, and some data after the wind storm.
A quick look at the latest control board for the VAWT. It is basically a buck type converter with a micro-controller that cycles the converter to achieve an average current draw from the wind turbine. The buck converter is based on an MC34063 and an ATTiny85 is used for the micro-controller. (8/31/14)
One VAWT spent around a year on top of a 20 foot post and exposed to the elements including more wind than I get at my location. It had some electronics to govern its speed, but it would spin up to a good RPM. The goal was to see how it would hold up over time. A few weeks ago it met its demise when the mounting bolts failed in a storm. This video takes a brief look at the VAWT after its time in the field. Overall, it fared quite well. The bearings turned smoothly without slop or noise. The wings that did not take the brunt of the fall looked to be in good shape. Although, some of the foam on the ends of the blades did not get good epoxy coverage and the foam was eroding a bit. While the LED failed, I believe the PMA and SCR/zener governor is working since it has been able to regulate its speed. (This video was originally posted July 26, 2014)
An update on progress with the VAWT 035 wind turbine. We had some wind today and for the first time there is evidence that the turbine could produce at least 20 Watts under reasonable wind conditions. I'm using a new controller based on an MC34063 buck converter and an ATTiny85 micro-controller. The micro-controller sends a PWM signal based on turbine RPM and current sensing to the feedback pin of the converter to control current. Although, it appears that the MC34063 is operating near its maximum current capacity. I think I might try the same approach using an LM2596.
A test to see if the speed data available on a web page matches the actual speed of the turbine. It seems to be fairly close, but there is a lot of variability in the wind and filtering/lag in the web page presentation so the results are inconclusive. Please note that this web site is not up anymore since I took down the wind turbine.
One criteria for determining the maximum tip speed ratio (TSR) is radial acceleration. Small vertical axis wind turbines must spin at a high rate to avoid aerodynamic stall. But that speed comes with high accelerations that put a load on the blades.
Just a quick look at the wind turbine set-up on March 23. I put it back up with a new battery and changes to the controller software. The controller now turns the MOSFET off for 4 ms out of every 200 ms just to make sure the MOSFET stays active. It is a work-around until I finish the new circuit.
We had a wind storm run through during the night. I left the wind turbine hooked up to see how it would react. I believe there is still a problem with the controller, or something was neglected in the software and the MOSFET turned off. That unloaded the turbine and it began to spin very fast leading to failure in the blades.
All the parts for the 0.35 m^2 vertical axis wind turbine together for the first time. The first VAWT 035 was put on life test. This is a second one that charges a battery through an input current controller board. We got a little wind, and it appears that all the components are working. It produced a peak of 10.6 Watts in a modest wind.
A challenge from a while back to build a wind turbine capable of producing 5 Watts of power for $25. This was my proposed design. The idea was to complement a small solar power panel with a wind turbine of approximately the same value.
Construction of a vertical axis wind turbine blade proposed by a friend named Steve as a possible improvement to the venerable Lenz2 blade. In retrospect, this blade did quite well. The only thing I had problems with is the small curve on the trailing edge. If that edge was straightened out, it might even do better.
Als Sturm werden Winde mit Geschwindigkeiten von mindestens 20,8 m/s (74,9 km/h) oder 9 Beaufort bezeichnet. Ein Sturm mit einer Windgeschwindigkeit von mindestens 32,7 m/s (117,7 km/h) oder 12 Beaufort wird als Orkan bezeichnet. Dazwischen spricht man bei 10 Beaufort von einem schweren und bei 11 Beaufort von einem orkanartigen Sturm. Erreicht der Wind nur kurzzeitig (für wenige Sekunden) Sturmstärke, so spricht man von einer Sturmböe. In der Regel sind mit einem Sturm auch starke Regenfälle verbunden, weshalb die Bezeichnung umgangssprachlich oft als Synonym für einen schweren Schauer oder ein Gewitter verwendet wird, beide stellen jedoch nur Begleiterscheinungen bzw. Spezialfälle eines Sturms dar.