Whirlwind Windscreen

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cruiser
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Re: Whirlwind Windscreen

Post by cruiser » Fri Oct 11, 2013 3:38 pm

LOL. That has the makings of a fine quote:

"My mind would be full of great ideas, if all my great ideas would stop distracting me." -Zelph

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zelph
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Re: Whirlwind Windscreen

Post by zelph » Fri Oct 11, 2013 4:00 pm

cruiser wrote:LOL. That has the makings of a fine quote:

"My mind would be full of great ideas, if all my great ideas would stop distracting me." -Zelph
Hey, I really like that :mrgreen: Over the years there has been a zillion great ideas come forth from members. Their threads are filled with cool things that are easily adapted to every day use. One thing that comes to mind is the "locking lid" for the original Heineken keg. The can be found in the Pimp My Heineken" thread.
http://www.woodgaz-stove.com/

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cruiser
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Re: Whirlwind Windscreen

Post by cruiser » Fri Oct 11, 2013 9:07 pm

The more I look at this the more it reminds me of an old video I saw on the fire vortex effect.

http://www.youtube.com/watch?v=jhoUXRRfwDA

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Re: Whirlwind Windscreen

Post by cruiser » Sat Oct 12, 2013 3:20 am

I was bored and so I started reading more and more and more about spinning and combustion, because the idea improving the fuel-oxygen mix seems interesting and possibly beneficial to combustion efficiency ... plus I am not hiking so I need something to occupy my time.

After a bunch of bopping around the inter-web, I found this rather simple description on the nakedscientists.com web site of what is happening inside a fire vortex where fuel vapor and air are not premixed prior to combustion, but rather mixed in a rotating manner as the combustion process occurs.

Why does the flame get higher?
As the air starts to spin there are two effects which cause the flame to grow:

ONE: The air is moving faster over the fuel so more of it evaporates, so there is more fuel in the flame, however this isn't the whole story (for example, if you blow on the fire the flames get a bit longer but not the 4-5 times longer witnessed by spinning).

TWO: When the air is spinning around the flame it is very hard for it to move inwards because centrifugal force is effectively throwing the air outwards all the time. This slows down the rate at which air and therefore oxygen can get to the fuel, so slows down the rate the fuel can burn. This means it will take longer to burn, so it rises higher before it finishes burning. The lack of oxygen also means that the fuel doesn't completely burn and it tends to produce lots of black smoke


So now I'm thinking spinning air might not be so beneficial after all ... faster evaporation rate combined with incomplete combustion don't seem to lend themselves to a beneficial outcome.

Still cool though.

(PS: Any conclusions reflected in the above are based solely on the work of Dr. Google, and may or may not reflect actual meaningful science.)

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Re: Whirlwind Windscreen

Post by zelph » Sat Oct 12, 2013 4:00 pm

Nice researching mr. google :D

The taller the chimney, the faster the intake of air.

A 6" tall windscreen(chimney) doesn't make it swirl very fast. The nice thing about it is the fact that it centers the flame under the pot. If you have one side of your windscreen open the incoming air will make the flame go off center of the pot bottom. Same thing if you put holes only on one side of the windscreen, think caldera cone and probably others do the same. This year I did a video of the C cone being viewed from underneath through a sheet of tempered glass and also using a mirror to reflect to the recorder what was occurring withing the cone. The flame was being pushed slightly off center. I also did a photobucket video years ago with a coleman lantern globe that showed the effect of having one side of the windscreen open. At that time Sgt. Rock over at whiteblaze.net was advocating having one side of the windscreen open, the side away from the prevailing breeze. and then there was the video showing how insufficient incoming air at the base of a windscreen causes incoming air to come over the top of the windscreen and caused radical flame formation due to air coming in from all directions. I was looking to have a laminar flow rather that turbulent.

http://www.woodgaz-stove.com/

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cruiser
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Re: Whirlwind Windscreen

Post by cruiser » Sat Oct 12, 2013 4:36 pm

Interesting.

So basically you want to use the swirling laminar flow of the entering air to contain and stabilize your flame? But I would think there is still a trade off with regards to oxygen availability even with the short height ... essentially the swirling laminar flow that grants you the stability on one hand, is equally robbing you of good fuel-air mixing conditions with the other hand.

I know you have been cleaning out your garage and throwing stuff away, but do you still have the center-draft "donut" aluminum stove shell Tony made for you?

I think it might be interesting to see how a center draft stove with a Starlyte wick material would react in this windscreen, where a ready source of air for combustion/mixing comes up from down low through the center draft independent of the swirling laminar "stabilizing" flow happening above ... meanwhile the Starlyte wick helps limits fuel evaporation with all the moving air in the system. (Although you might need to raise the bottom of the windscreen to get non-swirly air to come up from the bottom of the stoves center draft hole.) I know some high efficiency furnace designs introduce independent air streams at different points along the combustion zone to achieve different goals, including things like stability and combustion efficiency.

I would like to see you come up with a screen design that squarely knocks the TD cone off its throne.

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zelph
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Re: Whirlwind Windscreen

Post by zelph » Sun Oct 13, 2013 10:18 pm

This new design will be as good if not better than the caldera cone. I tried making one out of titanium but ti is too difficult to machine the louvers. This design and the use of the StarLyte stove to support the pot is the winning combination. Another design is the "square" windscreen/pot support that I came up with last year or was it 2 years ago.

The dual flame was recently copied by smokeeater and the guy never gave me credit for it. That's what happens when I share my stuff. :roll: He copied minibulls designs also. At first smokeeater was on my side as far as feelings for the guy with the funny hat. Now he and tinny love each other. :lol: So the world turns. ;)

Here is the thread showing the solid aluminum dual flame burner that tony machined for me. I still have it for sure. :D

viewtopic.php?f=2&t=427


.
http://www.woodgaz-stove.com/

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cruiser
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Re: Whirlwind Windscreen

Post by cruiser » Tue Oct 15, 2013 5:53 pm

I will be excited to see what you come up with.

I like the idea of a windscreen designed specifically for the Starlyte. The Caldera cone is a nice stable system but it has its weak points; lots of assembly required and a closure that becomes finicky after repeated use to name just a few.

Good Luck!

SSGHawk
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Re: Whirlwind Windscreen

Post by SSGHawk » Sat Apr 19, 2014 6:24 am

Yippeee!
I knew this was out there somewhere.

Got any updated thoughts?
Thanks for all of your wonderful ideas.
regards,
Paul

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Re: Whirlwind Windscreen

Post by zelph » Mon Apr 21, 2014 6:35 pm

Ok, there are different schools of thought out there. Some are thinking turbulence is needed for complete combustion of gases as they travel upward. Others say it's a moot point because the distance up the side of the pot is so short. Once the stove is burning hot the air movement is fast. I have gotten good results with the Modified StarLyte Burner having a plain smooth side windscreen to within 1/4" spacing of the pot. Test results over at backpackinglight are coming in positive also.

http://www.backpackinglight.com/cgi-bin ... startat=80

One thing I like about the louvers doing the swirl is the flame is kept directly under the pot. If there is a slight breeze there is no noticeable flame movement off center.
http://www.woodgaz-stove.com/

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