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gregadamson

wind turbine triple helix

by gregadamson Nov 17, 2018
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Well the other design proved to be super useless by 3DPVDB. Wasted so much filament dude put a 5mm shaft hole in it and I couldnt get it to spin on any set of bearings I had or made ina planetary form. So Now to test his trash design I have to make a 1.5mm walled spacer so the 5mm od shaft fits the 8mm id bearing hole and use like 6 and print a housing. Since Im not doing any of that to prove that guy is a complete moron. And wow. You have a 1/4 inch shaft hole as well. WHY!?!?!?!?!?!?!?! What bearing that will last more than a week takes a 1/4 inch or 6.35mm SHAFT?!

Sick of these trash useless designs designed for whatever crap electronics you decided to buy. Not even worth converting from mesh to cut a bigger hole in it. Just going to use my Ying Yang design because all you college grade idiots know all these formulas and can calculate everything but your own stupidity. I do what obviously works. Apparently whats obvious to me isnt to everyone else. You need an 8mm shaft hole to use bearings THAT LAST. Abec-9's are skateboard bearings that deal with more weight and decent roll time before being thrashed. since its much less weight on the bearing THEY LAST LONGER. Why on earth you use a dinky 1/4 shaft to mass your centric weight is beyond me. MORE WEIGHT DOWN THE MIDDLE = MORE MOMENTUM SUSTAINED! Plus I want a precision 8mm linear shaft thats been spun on a lathe, not some trash out of tolerance home depot 1/4 inch rod from china. Jesus dude THINK you do have a brain right?

I have that same printer! I upgraded to a 220mm radius aluminum heated bed and put a 32 bit smoothieclone on it to get it above 35mm/sec without removing the screen data in firmware. Wanna print a bigger one of this now that my 3 ft tall printer is done. did this work well?

And what is the rest of your project? Have you used a generator,...? Can we have more details?

I built a base with 2 bearings on the 1/4 inch shaft that runs through the turbine. I put it outside on the railing. It looks cool and it has done a lot of spinning. Originally I was going to incorporate a generator in the base but after calculating how much power I might get with a 1 foot tall turbine I decided not to. I do have an improved dual, counter rotating design with a director in front to improve efficiency.
The original helix could be stacked up for a taller version, maybe with a support top and bottom.

Very nice Greg! remind me where we met? The two blade/bucket vs 3 blade has long been discussed, and forgive me but without seeing your data or methodology, I can't see your conclusion as conclusive, though if it's supported that'd be great to know. I'd be interested to discuss your testing if you're willing.

The reason that I stuck with a two bladed design, vs three, is the 1970's blackwell report (available via my website artinventing.com ), where they showed that a 3 bucket design did produce a higher torque, but a 2 bucket design produced more total shaft Watts. Testing in the 80's (UBC ? Modi and Fernando?) also showed that a flattened bucket (more aerofoil like), increased total Watts (relative to surface area). This would be easy to mix up in testing.

I also am not sure you are correct about a helical 2 bladed producing vibration. Vibration was a common issue with the 2 bladed non helical Savonius, however a helical turbine should be able to always be presenting the same average sectional area, so shouldn't have that problem, and since Windside's 2 bladed helical Savonius has proven to be very reliable (though inefficient), we can safely say that 2 blades do not necessarily make for vibration problems (though some variations of helix may).

From a theoretical point of view, an advantage of 2 blades vs 3, is lower turbine solidity, and better air passthrough. A non intuitive, but primary problem of turbines is how do they get rid of the fluid from which they've extracted energy (and slowed down). A thought model is this, If a turbine were 100% efficient, at capturing the energy in a moving fluid, it would be "full" of motionless fluid. The Betz limit considers this. With the 3 blades, "dead" wind will fill the rotor, reducing flow through the rotor and forcing flow around the rotor. That's my thinking, and while I never tested a 3 bladed version, my 2 bladed versions tested to 35% efficiency, whereas the blackwell tests of the 2 bladed Savonius reached about 20%, and the 3 bladed closer to 15% as I recall. (all the blackwell results are questionable though, as incorrect wind tunnel blockage factors were used, so their results don't reflect real world, just relative within the tested variations).

Hi Drew. We met through Jon Scott here on Saltspring. I came to your house and you showed me some of your work. Certainly my testing is not conclusive re 3 blades as there are many factors to consider including scale.
It is interesting to hear what you say about the design.
Hope all is well with you, sincerely, Greg