Building the sickest ® VAWT ever. Brilliant minds unite please!!

[brandnewb]

And, the big distinction here is that I am printing from USB. Remember the long file name issue?

So it might well be that once I start printing from SD then the firmware gets to do it's thing in a more acceptable manner.

But here comes my paranoia again. The sooner I can replace the firmware to marlin the better. I don't like closed source code running on devices i have.

This is one supporting reason why I want a second printer. So that replacing firmware can go wrong without grinding to a halt.

 

[brandnewb]

Also Gary,

I do really thing it's the quality of the print bed. I am not one to already claim mastery but one thing I do have is good eye sight when I wear spectacles.

It's sooooo obvious to me this glass plate is of unacceptable quality.

It could be however that this kind of build surface is the norm and thus accepatable. and I just need to have a few kicks in the bud and get over these hurdles.

 

[justgary]

Also Gary,

I do really thing it's the quality of the print bed. I am not one to already claim mastery but one thing I do have is good eye sight when I wear spectacles.

It's sooooo obvious to me this glass plate is of unacceptable quality.

It could be however that this kind of build surface is the norm and thus accepatable. and I just need to have a few kicks in the bud and get over these hurdles.

Remember the part about getting the print bed clean before every print? I use a little alcohol and a clean rag.

 

[brandnewb]

So finally the printer is behaving again.

Turns out I had my first layer height too large and reducing it to 0.3mm (even though I have a 1mm nozzle now) magically solved all problems.

I did also clean the bed thoroughly.

I was able to print disks for the generator now in 1/3rds rather than in 1/4ths

So I just tried 96 magnets at 60 RPM in a traditional arrangement. Look how much larger the diameter got as opposed to a repelling arrangement.

Theoretically I could get a traditional arrangement with a similar diameter as repelling with 6mm spacing at the inner edge. But I forsee all kinds of stability issues then.


I got around 235 milli volts using a single coil of 9 winds. In a repelling arrangement it was about 177 millivolts.

5mm for a magnet disk is rather thin though so we'll loose some performance because of the overhead in resin that will be needed.
Also when repelling less of the magnet surface will be exposed to the heat of the coil disks. That can only be a good thing won't it?

It might well be that a repelling disk is simply just more efficient when we also take ease of construction and life time endurance into account.
@Hedges would you have any insights/ideas on this all with a helicopter view?

 

[brandnewb]

It might well be that a repelling disk is simply just more efficient when we also take ease of construction

Please allow me to elaborate.

I have complaint before about how difficult it is to construct a repelling disk. And it was using my newb method. Meaning just going magnet by magnet.

However, if we glue magnets into place every other, so skipping one, then they attract.
Once the glue has dried one will have much less of a battle getting the other magnets into place.

 

[brandnewb]

it fits.. maybe too tight. I am a bit worried about the induced stress after banging the blade section on the tube.

 

[Hedges]

Hmm, I've been following this thread since the beginning, but last update I was notified of by email was June 13 2022 (and I did open that.)
Forum notification hasn't told me about more recent posts, such as #741 at top of page, which occurred last Friday.
Maybe my posting again will renew following.
I've probably replied to more than 1024 threads and memory started to leak. Or whatever its limits are. Forum software suffers from Alzheimer's? Or do I?

 

[stienman]

Email updates are queued, and occur periodically depending on the forum settings - for instance daily for many forums.

If someone posts, it adds the thread to the email queue. If you post before the queue is sent, then it removes the thread from the queue.

You post frequently, so you won't receive a notification unless someone posts and you don't post for a day or so after their post.

 

[stienman]

Actually, this forum might have immediate notifications enabled. Even though I'm actively browsing the forum, it did send an email within a minute of someone @'ing me in a post.

 

[brandnewb]

I guess we mere mortals all suffer from some form of altheimer, in varying degrees, every now and then.
There is this film 'the father' in where Anthony Hopikings does a supurb job.
I recommend it.

It's a serious topic.

 

[brandnewb]

Email updates are queued, and occur periodically depending on the forum settings - for instance daily for many forums.

If someone posts, it adds the thread to the email queue. If you post before the queue is sent, then it removes the thread from the queue.

You post frequently, so you won't receive a notification unless someone posts and you don't post for a day or so after their post.

Nah, the outgoing data flow of this forum software is bugged I think. I have noticed for a long time. Now the fact that when outgoing emails do get send it is marked with a 9+ sSPAMM score. that's bad ;(

One could argue then to simply add this forum to the whitelist yes?
Yes, but that did not address the first concern in where not all messages are being sent all the time.

just my 2 cents as an engineer

 

[brandnewb]

Hmm, I've been following this thread since the beginning, but last update I was notified of by email was June 13 2022 (and I did open that.)
Forum notification hasn't told me about more recent posts, such as #741 at top of page, which occurred last Friday.
Maybe my posting again will renew following.
I've probably replied to more than 1024 threads and memory started to leak. Or whatever its limits are. Forum software suffers from Alzheimer's? Or do I?

Welcome back brother. I do have missed you. Can you please take a bird's eye view on the 2 magnet disk options we have?

 

[brandnewb]

@Will Prowse may I suggest you simply restart the server? Or do you have any kind of health monitoring going on?

 

[brandnewb]

Also when repelling less of the magnet surface will be exposed to the heat of the coil disks. That can only be a good thing won't it?

I'll be honest now. I feel like am creating a logbook more than anything,

Sure many of us are pitching in with each their own expertise and that is exactly how it's meant.

But is one really interested to know where this all leads? in other words shall I only come with questions or is one interested in the journey as well?

 

[Will Prowse]

@Will Prowse may I suggest you simply restart the server? Or do you have any kind of health monitoring going on?

Everything looks good from what I can tell. Can you define the exact issue? Blacklist of email coming from this site? Even my personal email is blacklisted. Not sure what would change if I restarted the server. I don't think I can do that regardless or how that would fix an email issue.

 

[Hedges]

I read my spam folder, nothing diverted there.
It seems to me the forum just doesn't always notify me of updates to threads I've been posting on. Like this one, had last notified me June 13th. (did get a message today, after I posted to it this morning.)
Maybe I opened that email but didn't click link to read thread? I suppose that might cause it to not trigger another update.
But I've noticed a lot of threads I follow come up under "What's new" without my having received email notification. I think even with days old messages I hadn't seen.

Something else I'd like is to receive an email when someone posts @Hedges , but that may only be under noted the bell icon, lost in a sea of notifications. Couldn't find a way to turn on email for that.

 

[Warpspeed]

Its all conceptually fairly simple.
First build the wind/water turbine of your dreams, then measure its actual mechanical power output.

So you then find that in the most typical most common wind conditions at your site, you measure a peak in output power at X rpm, and Y ft/lbs of torque loading, using a mechanical brake and a tachometer. Plot the rpm/torque curve to find the actual peak.
Power will peak just before blade stall, then fall away very quickly with higher loading.
File all that information away for future use.

Next step is, you now know the shaft power available, assume a generator efficiency, it does not need to be very accurate, but lets say 500 watts output for example. Now if your system voltage is 48 volts, that is going to be very roughly ten amps.

So you wind your alternator with suitable wire gauge to be able to safely carry the ten amps of expected rectified dc current.
Now without needing to know the magnetic flux density, number of turns, air gaps, number of magnets, or overall diameter, you build your alternator to whatever design looks to be about right, based on what you can find out from other peoples successful projects.
Even if its rather different, its still going to work fine.

So you have now completed building your new mystery alternator and its ready for testing.
The only thing you know for sure is the windings must carry the required final ten amps. What you don't know is how fast you need to turn the thing to generate the required 50 or so volts. If its big, with strong magnets and lots of turns, probably not all that fast. If its a bit on on the small side, it might need to turn pretty damned quick to generate 50 volts. But regardless, its still going to work and generate 50 volts and 10 amps.

Anyhow, hook it up to some means of spinning up the alternator to test it. Find out at what rpm it needs to turn to generate 50 volts when loaded to ten amps (a five ohm 500 watt load).
You have already established the operating rpm of your turbine, and you now know the required alternator rpm.

The last step is fitting a mechanically efficient drive of a suitable step up ratio to achieve the required alternator rpm.

 

[brandnewb]

thank you for taking the time to lay that all down.

Given my early test results I think I will be looking at 31 winds per coil to reach 58.4 volts at 60 rpm.

The worrying thing though is that I was warned on another forum that at 60 rpm, in the context of my planned 2m diam turbine) the Tip speed ratio (TSR) would be so sub-optimal there will be no power to be had.

As I have no idea what this all means and how to take more related aspects into account I am just going to have to trail and error things out.

Now increasing target rpm is an option and I can design the generator to spin at let's say 120rpm or even faster. Sure that is good news for the coils as then we can use thicker wires and less turns but I'd like for the turbine to stay save to operate in an urban environment.

This local code is just too restrictive.

 

[brandnewb]

So you then find that in the most typical most common wind conditions at your site, you measure a peak in output power at X rpm, and Y ft/lbs of torque loading, using a mechanical brake and a tachometer. Plot the rpm/torque curve to find the actual peak.

Could you please elaborate a bit more on this? A tachometer I have and also this luggage weighing measurement thingy I thought I could use for torque measurements later down the line.

I would very much like to learn how to collect data to be able to plot this graph you speak of.

 

[Warpspeed]

O/k the tachometer to measure rpm is pretty obvious.
Measuring torque is a bit more interesting.
Back in the days of steam engines they used a "Prony Brake" to measure developed engine torque.
https://en.wikipedia.org/wiki/Prony_brake

As engines became a lot more powerful, the method became impractical, because a friction brake would just quickly burst into flames !
But for our wind/water turbines its a perfectly simple and practical way to measure torque output.

The idea is you start out with your turbine unloaded and measure the rpm.
Then you apply a minimal resistance to the turbine by adding some small weight to your Prony Brake.
The friction load slows down the rpm, but now its delivering measurable torque, depending on the weight and the radius of your brake.
If you multiply rpm x torque you can calculate horsepower.
James Watt did all this a very long time ago, and a bit of Googling will get you the whole interesting story.

Anyhow, you gradually add more weight and load to the turbine, it keeps slowing down, but the torque keeps increasing.
The measured power keeps increasing too, up to some point.
Beyond that, if you overload the turbine, the reduction in speed becomes greater than the measured increase in torque, and measured power falls.

There will be a definite peak in power at some particular rpm for any given wind speed.
If you design your alternator windings and alternator drive ratio around that, you cannot go too far wrong.

It may not be perfect for very low wind speeds, or storm conditions, but if you do your tweaking at typical wind conditions at your location, it should not be too far from an optimum design.