[TheForge] Gas forge burners

[Jerry Frost]

I find myself replying to my own post but it was pointed out to me the
"swirling water in the bottle" experiment isn't a valid demonstration of
increasing flow with a vortex.

It only works in a bottle if there is no air hole in the bottom. It
increases flow because it creates a free area in the center of the vortex
for air to replace the water in the bottle. It's only faster compared to air
bubbling up through the water. If there is an air hole in the bottom of the
bottle it actually flows slower.

I haven't tried the experiment with an air hole in the bottle but the
explanation makes good sense and I have no reason to doubt the person who
clued me in.

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.


----- Original Message -----
From: "Jerry Frost" <frosty@customcpu.com>
To: <theforge@mailman.qth.net>
Sent: Friday, April 09, 2004 9:49 PM
Subject: Re: [TheForge] Gas forge burners


>
>
> ----- Original Message -----
> From: <Keporter@aol.com>
> To: <theforge@mailman.qth.net>
> Sent: Friday, April 09, 2004 10:54 AM
> Subject: Re: [TheForge] Gas forge burners
>
>
> > So, the best kind of
> > turbulence is that which does the least to "put the brakes" on forward
> motion.
> > Spinning the gas/air mixture gives the maximum mixing action for the
> minimum >drag.
> >
>
>
> Ah vortices! I love vortices, they're such useful things. <grin>
>
> Bernoulli (I'm not sure why Venturii gets the credit) noted that: gas
> flowing smoothly (laminar flow) along a curved surface accelerates and
> creates a vacuum between itself and the surface. The vacuum at the
interface
> greatly reduces friction. Interestingly enough it doesn't seem to matter
how
> it flows, inside, outside, (over, under) across or along there's a
pressure
> drop and velocity increase. Flowing across yields a greater effect than
> along a curve however so even though gas flowing through a pipe enjoys
some
> effect, it's not nearly as much as if it were flowing across a pipe.
>
> A vortex inside a pipe or outside one for that matter can cause a strong
> vacuum and significant velocity increase, depending on the angle of attack
> and initial velocity.
>
> As Mike says a good vortice will do a number of positive things for a
> propane burner:
>
> The first thing it does is strengthen the vacuum on the intake end.
>
> Secondly it keeps the air and propane together in the tube longer before
> ignition.
>
> Thirdly the low pressure environment makes the air and propane mix better.
>
> A strong vortex unfortunately requires a lot of precision to control. If
the
> tube has any irregularities the flame will be off center or dance or maybe
> do something really interesting.
>
> For an easy example of just how much a vortex will improve flow: Fill a
> largish 2 litre clear soda bottle with water, upend it and time how long
it
> takes to drain. Now, refill it and after you upend it give it a little
swirl
> to get the water spinning. Just a little, half a flick is plenty and time
> it.
>
> The difference is easily visible but putting a clock on it really makes it
> real.
>
> Frosty
> ------------------------
> If it ain't forged
> it ain't real.
> Wrought iron is.
> The FrostWorks
>
> Meadow Lakes, AK.