A combination of a 200mm diameter Darrieus and a 80mm diameter Savonius VAWT. A friend of mine coined the term Darrivonius, so I thought I'd start using it. This turbine is a trimmed down version of the previous one to reduce drag and get more airflow through the turbine. The jury is still out as to if it is an improvement, but it seems to do okay.
A combination Savonius / Darrieus VAWT where the Savonius part could be repositioned relative to the airfoils. Zero degrees is where a line across the scoop openings is inline with the airfoils. Tests were run every 20 degrees going counter-clockwise, but in random order. Unfortunately, the wind speed data was not visible in most clips so it is of marginal benefit. I wanted to post this so I could share the data if any can be gleaned from it.
This is a VAWT with thick airfoils in a good wind. I was going with the thick wings to help them start in low wind. However, I'm not sure that is the best strategy since they don't go all that fast in a strong wind. That is a good thing for protecting the VAWT from damage, but not so good if your alternator is weak and you need the speed to get enough voltage to light some LEDs. However, it did manage to spin fast enough for light.
A quick test of an NPL EC series airfoil with 67mm chord and 40% thickness. It is bent around the radius with no additional mounting angle. It seems to start in lower wind and accelerates smoothly. So it appears to be an acceptable wing. Efficiency probably suffers from the large wing.
A look an airfoil that is a compromise between the Lenz2 style and the purely lift versions of the turbine. My hope was to design a turbine that would turn in low winds like the Lenz2 but have lower drag and spin a little faster in moderate winds. The result is inconclusive because our winds have been so light or from the wrong direction for the past few weeks. I tested it using the car, and it appeared to behave as expected.
I did not have magnets in the rotor at the time of this video. Eventually, I want to mount the magnets and include a joule thief circuit to light an LED while running at lower RPMs.
A Joule Thief circuit for possible use in driving a white LED from a low voltage source.
This was not my design. I got the circuit from the Alternative Energy Forum -etc..
Please note: the direction of the winding around the fixed inductor.
A brief test of a small VAWT modeled after the popular DIY "Lenz2" design. However, instead of having a circular leading edge and straight sides like a Newman Circular Nose airfoil, this one uses an NPL EC airfoil that has an elliptical leading edge and cubic sides. In keeping with the Lenz2 design, the solidity is 1.0 which is higher than my previous models, and the airfoil has a thickness of 46% which is high compared to the others. Also the trailing edge is rotated inward 15 degrees about the mid-chord point as with the Lenz2. I also curved the airfoil around the circular path that wing travels. I don't know if that is a good thing or not, but it seemed to make sense to me. The result is a turbine that starts turning in a light wind and seems to increase speed smoothly as the wind speed increases. I don't know yet if the RPM will be high enough to light an LED, but it looks promising.
The final version of the 3D printed VAWT with 90 turns of 32 AWG wire to allow it to light a white LED directly with no electronics to boost the voltage. It was printed in PETG material for outdoor use and mounted in a garden as a decoration. With a good breeze, it should provide some light for added interest.
I wanted to try bending an airfoil to match the curvature of the turbine rotation since the blade is so wide compared to the turbine diameter. I was pleased with how well it spun up, but disappointed with how it did not want to start spinning from a standstill. I might have to move the tail end inboard a few degrees. Anyhow, it is time to take the best attributes of the previous versions and come up with a final design.
Just documenting behavior of a VAWT with four 40mm NACA0024 wings, and another run of the original wings for comparison. I still like the three winged version best, but the four wings seemed to start turning easily. Three wings provides a wider and sturdier blade, but I still don't like how the blade is designed as if it was going through steady airflow when it is actually rotating rapidly. But that will be addressed by the next version.
I tried lowering the solidity of the turbine and changing the airfoil. There was no wind in the forecast for the next week, so I decided to test the turbine using a vehicle. The results did not look very good so I'll try something else. I uploaded this video to document the results of the test.
There was a little breeze today. Here is some video of the VAWT spinning. It was actually moving pretty good and looking a little distorted in the video. The next step is to but the magnets on and see if it will produce a little power. I'm just looking for something to light an LED, so not all that serious of a power source.
The goal of this project is to take a guitar input and output a frequency that is half that of the input; dropping the signal down an octave. I was hoping to use a fairly simple technique using an ATTiny1614. After looking at the signal, I think this might be very hard if not impossible given the planned circuit. But I want to give it a go anyway. There is an anti-aliasing filter on the input. It might be the reason the higher notes have such a low output and the filter might be shifting the phase of the overtones.
Just a quick video to bring closure to this prototype. It did not spin well in the past because the pivoting part would wedge on to the wooden arm and stop it from spinning. I added some bits of tape to prevent that and it appears to spin quite well. It started despite being only two wings. The pivot would swing a lot as the turbine came up to speed or was under a load and then settle down to minor movements.
Created 4 years, 1 month ago.
Category DIY & Gardening
Documentation of various DIY projects related to Engineering.