Savonius & Gorlov VAWT
Derived from
Description
NACA 0015
Instructions
This design goes back to the NACA 0015 profile used in the first designs, with the addition of a Savonius for self starting. The Savonius size is chosen to run at it's optimal speed when the Gorlov turbine reaches it's optimal speed, preventing unnecessary drag.
Print a top and base, and at least 2 atomic sections.
There are no dove-tail connections yet (coming soon) so be careful when assembling.
The turbine is designed to be threaded onto a 8mm threaded rod. Assemble and glue from the base up, leaving the top section free to rotate in order to get the captive nut in. Glue, allign and push printing filament of your choice through the holes in the blades. Currently configured for 3mm filament, but you can choose any size in the scad file. This will allow other materials like thin aluminium rod etc. to be used.
Given the effect the Savonius section may have on the Gorlov turbine it may be better to print three atomic sections with the support wings. This will make assembly easier, while keeping things balanced.
Almost every aspect of this turbine is now parametric, and while this design uses a Camber of zero, it is very easy to specify the camber for experimentation. A recent study suggested that a camber selection of 2 may aid self starting without the use of a Savonius turbine, but that it will influence the maximum torque that can be harvested.
This version also incorporates a lot of changes to the basic structure to ensure easier assembly and strength thanks to the very nice report written by Imitation on the last published version of the turbine.
It is definitely a work in progress. It is currently only hampered by my unfortunate lack of 3D printer. There are already plans for an integrated base and printable generator on the drawing board... Watch this space for more.
PS: Updated scad file: I had problems with MCAD again - OpenSCAD crashed frequently on my system given the workout I am giving it with this design...
Another update! Thanks to t00tie - fixed a bug where only the default guide hole size propageted in the turbine, even if you set Guide_hole to something else.
Added the Base + Atoms STL requested by eat808.
Added inverted Atom requested by eat808.
Updated SCAD file (mk7)
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Hi qharley,
What's the difference between the SCAD files and STL files? and which is needed to print ?
Thank you
Hi qharley,
What's the different between the SCAD files and STL files? and which is needed to print ?
Thank you
Hi qharley,
Why did you incorporate a Savonius rotor in the design? I thought the Gorlov helix type wind turbines were self starting (correcting one of the problems with the original Darrius rotors) ?
Hi qharley
Scratch that last comment, I have exported just the Atoms blade flipped (I used blender) and after printing the malformation is present on the trailing edge as well so it must just be a trait of trying to print ABS of such a small footprint on a hot bed, I may have to tinker with cooling the hotbed immediately after the first layer has stuck to see if I can minimise the distortion.
I am now printing in yellow ABS so it should looklike a mad bumblebee when finnished
So forget the upload I asked for and thanks
I will post another pic soon
Graham
Hi qharley
I have discovered that the malformation on the leading edge (visible in photo) is only present on the Atoms and not on the Top & Bottom bases.
This seems to be due to the "overhang" being on the leading edge of the blade on each subsequent layer on the atoms.
This has the undesired effect of curling on the (first 1-2cm) of the leading edge resulting in the malformed leading edge, this is probably due to me printing using a RepRap style printer in ABS using a hotbed (as I guess most people are, what is your printer build based on?)
The Top bases are printed from the top (i.e. flipped) this has the effect of the next subsequent layer always overhanging on the trailing edge of the blade and as there is a lot less plastic on the trailing edge it does not curl.
I have loaded your OpenScad files to make these adjustments myself but I am guessing that the atom would need to be generated differently (beyond me at the moment I am afraid).
Could I ask you to post the "Atom Without Support Strut" so that it is flipped and printed from the other end, this would have the effect of the next subsequent layer always overhanging on the trailing edge this gives a much better quality leading edge and would avoid the curling issue completely.
seeing as the Atom without support also has a centre bush (which if you literally flipped the stl would be hanging in free space) you could separate the bush into another stl and just flip the Atoms blade and save this as a separate stl.
I am not sure why the issue is not so present on the bottom base, it may be due to there being the 3 support struts and 3 blades as this gives a lot more time for cooling between layers (i.e. there is a lot more to print on each layer of this part giving time for the layer to cool properly)
I hope this makes sense, I have tested this several times and the curling only ever occurs if the next layer is overhanging on the leading edge of the blade.
Sorry to ask for more uploads but as I am a newbie at OpenScad I am stuck.
Also the last part you uploaded (when I eventually finish my Rostock build) was short 1 bit but don’t worry as now I have played with the OpenScad file I realise that you have Para-metricised the whole thing so people can simply select module "1" for the whole assembled thing (cool) and print it on a Rostock or other printer with large build volume.
Many Thanks for such a cool thing
Graham
Hi qharley, "minor flaws?" where? the only issues I mentioned in my blog are due to my printer's build quality & retraction settings, the friction I mentioned in my previous post here is about friction in the planetary gear set that I would have liked to use to decrease the speed and increase the torque on the output shaft of this cool little wind turbine blade set (slower speed & more torque needed to lift water mechanicaly).
As far as I can tell this/your VAWT is perfect (but then I am not an aerodynamic's expert like you) I am sure once you have your own printer running you will be posting improvements/upgrades.
Any chance you could post a complete (assembled) module (i.e. top, base & 2 atoms all joined in a single stl) for those of us that have access to a large printer such as a Rostock, one with Savonius and one complete module without Savonius (preferably without the extra support wings that are needed when printing this as several parts)
this way people who have a rostock running could print the whole thing in 2 parts. (maybe even one single part if the Rostock is tall enough)
I will post more pics & video once I figure out how to use youtube!(afraid I am not digitaly native, to old, as demontrated by my sad looking blog)
Love this thingi, Keep up the good work & thanks.
Graham (eat808 aka sexstrap)
Hi Graham,
"Flaws" firmly in the cheek... Haveing no printer I only have one major flaw... No print at all!
Sure, I could make a single print model. I will create one tonight when I get home. It is also quite easy to make one yourself using the OpenSCAD files, but understand that any form of programming can be daunting to some in the same way any type of accounting could be to me...
Cheers,
Quentin
This VAWT works a treat, I have held this up in a strong breeze and it self-starts and spins up nicely (sitting on a 608 bearing), I have yet to make a frame to mount it on but it's coming soon.
I have every intention of trying to get this pumping water directly (mechanically) out of a well using other printed parts such as the tiny planetary gear set http://www.thingiverse.com/thi...
to increase torque and lower speed but it has a fair bit of friction in it. there is a larger set http://www.thingiverse.com/thi...
that may have less friction (gear teeth are less rounded).
I may use a printed diff such as http://www.thingiverse.com/thi...
I would also like to try it with the axial flux generator http://www.thingiverse.com/thi...
This is actually one of the previous derivative I will update the photo once I have printed one of this derivative.
I am even thinking of building a much larger printer maybe a Rostock http://www.thingiverse.com/thi... just so I can print these in one go or just a lot larger.
My thanks go to qharley for running such great CAD project such as this one, keep up the good work I for sure will be testing any improvements.
Liked this so much put it on my blog, (shameless link to blog) http://sexstrap.blogspot.co.uk...
Graham
PS: When you have your water wind-pump running, we want to see a thing and a video.
Your post made my day. Except for the minor flaws you pointed out, the turbine looks absolutely great. I am in the final straight of building my own breed of repstrap, and besides a couple of printer parts, this would be the first thing I would like to build. I think I have waited long enough...
Cheers!
Quentin
Thanks for this great work :)
Might it be possible to integrate the profile of M. C. Claessens (DU 06-W-200), developed in his master-thesis on airfoils for VAWTs while comparing it with NACA 0018?
See his thesis here: http://www.lr.tudelft.nl/filea... See p. 75 for profile-comparsion with NACA 0018 and p. 95 for coordinates.
His profile has a thickness of 20%, camber of 0.8% and is - tada - non-symmetric. Right now I got the x-y-coordinates converted to a DXF and wonder how to put it in your scad :)
Great job. The holes print too small so I enlarged them and found a minor buglet: You define Guide_hole but use guide_hole in module helical_wing. Hope you get a printer soon and continue this!
Hi qharley
Why did you chose that type of airfoil (NACA 2415)... over something else? and what is the angle of attack?
d.
Angle of attack is 0. See my previous turbines. Adding angle of attack will improve the self starting ability of the turbine, at the expense of torque. That is not a good trade...
2415 is a profile used by many turbine manufacturers. it has a relatively thin profile while still delivering decent power. Remember that the blades turn at approximately 2 times the wind speed (and three times coming around on the opposite side)
I will do more experimentation on this when my r
epstrap is complete. I have taken the long hard way over the quick way, and though I regret some aspects of that decision (like not having a printer RIGHT NOW) It will pay off with a decent build envelope when it is done.
I look forward to your developments :-D would you do a water vortexer sometime?
hmmm.... on second thought, can the PLA or ABS used in RepRap to print this VAWT be able to withstand the outdoor conditions and UV ?
why didnt you take a 3 winged savonius?
would have had a lot more symetry thereby will vibrate much less when turning
The savonius design I took is based on a recent study to find the most effiecent simple savonius turbine. It comes down to this:
1. The cups should be twice as high as they are wide
2. Two cups should be used
3. The overlap (with open channels beween cups) should be between 15 to 30%
My savonius is only intended to start the much more efficient Gorlov.
The two cupped savonius is quite balanced on its own, even if it does
not seem to match the three bladed gorlov.
Fantastic work on this! I'll try print it soon and let you know how it works for me.
Looks intriguing, and I love the idea of printing a wind turbine, but I have to wonder whether it's possible to 3D print something large enough and light enough to actually work. Hopefully I can print it soon (waiting for the printer to ship).
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