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Re: Alternate energy

Postby Sparkicidal » Tue Oct 09, 2012 8:48 pm

Cowboybob wrote:Here are the results of the "wind speed test" that Col. Briggs helped me perform yesterday at the
Citadel Military College here in Charleston:

Resized Wind Source speed tests (Kts).jpg


Note the wind speed recorded for the floor fan (set to max [#3]) at the 25cm position, which is about
twice the distance from the fan position in the previous pic of the WATT prototype.

Pretty close to my estimate of 10-12 knts, I'd say 8-). (Enough of your self-congratulatory crap, Cowboy...)

Anyway, it gives me the energy range capabilities I can expect from the WATT (for the task at hand), given the
seasonal average wind speeds on the Atlantic along the route I presume AB will be programmed to follow (and the
route I assume AB will actually take :o ).

Now, on to building the durn thing :D .

CBB

I apologise if I come across as impolite here as I've had a rough day at work, but unless I'm missing something, I don't see the point of these tests. You worked out that the further away from the source of the wind, the power of said wind is less? If you'd produced a wind speed vs power output from WATT, then it would make more sense, but I don't see that in your results.

I love what you're doing here so I don't mean to offend you, I just don't understand the validity of this experiment from the data you have provided. Is there any other data you collected or method statement you could show that could clear the fog in my mind...?
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Re: Alternate energy

Postby Cowboybob » Tue Oct 09, 2012 10:12 pm

nathan wrote:That looks brilliant... But I'm not sure I understand. Am I right in saying that at 10-12 knots is when it's most economical?

No, I'm just confirming that my "test bed" is mimicing the wind speeds AB will generally encounter on it's trek. I'm not attempting to suggest any sort of economical aspect, just the accuracy of my assumptions. Just trying to build something useful and designed for the task ahead.

nathan wrote:I'm sure I've ran through the Charlston College when I was touring the US a couple of years ago, is there a sort of ruined castle you can walk around near by?

Yeah, there is. I think you're referring to the old Charleston Jail (which interesringly enough, our family owns). I't's currently being used by the Charleston College of the Building Arts, a degree institution for teaching old construction trades, i.e., like stone, black (wrought) iron, plaster and wood techniques. Something akin to the European "Craft Guild" concepts.

Sparkacidal wrote:I love what you're doing here so I don't mean to offend you, I just don't understand the validity of this experiment from the data you have provided. Is there any other data you collected or method statement you could show that could clear the fog in my mind...?

Sparkacidal,

This test was just to confirm the validity of the output of the fans I'm using.

I didn't want to predicate ANY of the design (and subsequent power production estimates) on a scenerio of potential, known available ocean wind speeds (which I want to mimic) without first confirming the output of my "wind" producers.

I can now proceed (actually have already started) with savonius/generator dimensions and construction (while making accomodations for the available deck space).

I'm also persuing and designing the electronics that will convert the generator's output (low level AC [<0.4VAC - 6VAC]) to a usable, reliable 5.1VDC trickle charger for the Lithium battery storage to power the Iridium package, which will suck 1.5ADC for 40ms each use (which I figure will be a max of once a week, excluding emergency comms).

I believe this package will suffice, but I don't want to make any unecessary mistakes by assuming anything.

Please don't forget that a savonius rig of this size and use hasn't been built before. I'd like to get it right the first time.
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Re: Alternate energy

Postby Sparkicidal » Wed Oct 10, 2012 10:02 am

Cowboybob wrote: This test was just to confirm the validity of the output of the fans I'm using.

I didn't want to predicate ANY of the design (and subsequent power production estimates) on a scenerio of potential, known available ocean wind speeds (which I want to mimic) without first confirming the output of my "wind" producers.


Bugger, sorry! My bad! I've just re-read your previous posts with a fresh set of eyes and I realise how I've got mixed up. When you did your original experiments, I thought you had the anemometer there with you, on the re-read, you say you were going to borrow one another day. This is why I questioned your experiment, but now I understand why you did it and agree with what you did.

Moving on from my blatent blunder, I do have a question about the design on the "blades" of the rotor. I have a concern that if the boat tips over, that the blades will act as scoops and hinder the SRiMech as they will fill with water. I was wondering if we are able to produce the blades so that they are open ended to mitigate this risk as much as possible? I'm assuming this would be a bit of rounded alu very much like the drinks can you have used for the prototype. Either that or it's printed in 3D. Actually, could you use a drinks can like you have in the prototype? It should be light, strong enough, very cheap and you get a refreshment whilst you make it? Or am I leaping ahead and being a pain in the ass? :)
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Re: Alternate energy

Postby Cowboybob » Wed Oct 10, 2012 1:17 pm

Sparkicidal wrote:
Cowboybob wrote: ...Moving on from my blatent blunder, I do have a question about the design on the "blades" of the rotor. I have a concern that if the boat tips over, that the blades will act as scoops and hinder the SRiMech as they will fill with water. I was wondering if we are able to produce the blades so that they are open ended to mitigate this risk as much as possible? I'm assuming this would be a bit of rounded alu very much like the drinks can you have used for the prototype. Either that or it's printed in 3D. Actually, could you use a drinks can like you have in the prototype? It should be light, strong enough, very cheap and you get a refreshment whilst you make it? Or am I leaping ahead and being a pain in the ass? :)


Actually did enjoy the ginger ale prior to using the cans for the rotor blades 8-) .

As for the rotor blades (buckets) and water retention:

Definitions ("d" = diameter of the bucket).
S Bucket gap width.JPG
S Bucket gap width.JPG (14.08 KiB) Viewed 24728 times


Explaination
Gap width performance.JPG
Gap width performance.JPG (35.86 KiB) Viewed 24728 times


Example design
2 Bucket Savonious Design.JPG
2 Bucket Savonious Design.JPG (29.3 KiB) Viewed 24728 times


As you can see, the gap between the buckets is essential to the performance of the rotor and nicely provides the rotor with a means to "dump" any water that might get into the system (interestingly enough, there is a water (tidal) driven example of a submerged savonius).

Low weight (mass) of the rotor, as you point out, is preferable. The AL cans suit that bill, but will corrode rapidly, especially since there will be ambiant currents (due to proximity to the generator) induced into the metal. Thus, I'm using a light weight HDPE (vitamin pill bottle material) for the final version, which is all plastic.

And, no, don't mind at all having extra eyes on this project. Any and all help, especially on a effort as fraught with possible "gotchya's" as this one, is more than welcome :D .
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Re: Alternate energy

Postby Sparkicidal » Wed Oct 10, 2012 9:13 pm

Okay, I see what you're saying but I was (obviously badly) referring to the bucket shape that is present on your prototype. I think it's diagram time:

Rotor.JPG
Rotor.JPG (17.88 KiB) Viewed 24724 times


Not bad for a quick 5 mins of CAD work at 10pm. On the left hand side of the picture is what we have now that could hold water. What I'm asking is should we design it like the diagram on the right hand side to help water escape? However, if so then the rigidity of the blade could be compromised and it could reduce the power output, but for now, I'm just throwing design considerations out there. :)
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Re: Alternate energy

Postby Sparkicidal » Wed Oct 10, 2012 9:15 pm

Actually, thought number 2. We could just have a supporting bar across the "top" of the blade to ensure it holds it's curved shape, basically where I deleted the line in the diagram to produce the open blade. Does that make sense or am I CAD'ing again? :D
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Re: Alternate energy

Postby Cowboybob » Wed Oct 10, 2012 10:37 pm

Have you noticed that the right hand portion of the posts gets cut off? I think this has been the case since the "Donate" banner went up.

Sparkacidal wrote:Not bad for a quick 5 mins of CAD work at 10pm. On the left hand side of the picture is what we have now that could hold water.

Only one bucket at a time would face up if in a horizontal situation. That bucket would instantly turn on the axis of both
buckets, releasing any water (and its weight) as the AB rights itself.

The assembly will not be an impediment to AB righting.
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Re: Alternate energy

Postby nathan » Thu Oct 11, 2012 8:57 am

I'll get rid of the donate button tonight if it's messing around with lower screen resolutions.
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Re: Alternate energy

Postby nathan » Thu Oct 11, 2012 5:31 pm

Also forgot to mention. You can get to the forums using www.autonboat.com/forums.
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