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43044Re: [hobbicast] Mikey re Vortex Burner

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  • mikey98118
    Jun 24, 2014
    • 0 Attachment
      Hi, Howard.
      Dan is right.
      You probably heard the arguments for venturi versus fan-blown burners back when you were researching just what kind of burner you wanted to build, yes? Well this burner is neither one and both at the same time. It does have a fan mounted on it, BUT, the fan isn't there to develop air pressure; it's there to develop air swirl. This burner series also employs the venturi effect to entrain air, just like Mikey burners do. The result is a burner that will put out a highly variable total combustion single wave front flame, just like the best venturi burners, but which can be turned up beyond fan-blown rates, while still maintaining a compact hot flame output.

      The central operating principle for these burners is found in the laws of vortical flow; a part of fluid dynamics: http://en.wikipedia.org/wiki/Vorticity
      For those who aren't in love with college physics:
      (A) Any fluid (including air) moving through a funnel shape, will spin as it travels between large entrance and small exit points within the funnel, creating vorticity.
      (B) Any fluid  traveling within that funnel will spin faster the closer it is forced to its axis (just the opposite of what happens on any point of a conical shaped solid).
      (C) Forward motion of a vortical flow tends to reach about one-half its rotational speed.
      (D) The fluid in a vortex will develop a low pressure area in its center, because of point "B".
      All of these factors tend to create a very positive gas/air feed at a burner mixing tube's entrance; thus the miraculous improvement any funnel shape makes in the performance of a linear burner; in fact such burners are totally unstable without a cone or bell shaped restriction at the air entrance.
      Now, supposing you put a squirrel cage fan at the funnel's air entrance; the standard practice on fan-blown burners. You will PUSH more air through the burner, but you have to baffle the fan because you quickly get too much air pressure for the burner nozzle to handle. Thus, you have to severely limit the amount of  air in your air/gas flow, or blow the flame off the end of your burner.
      Up until recently axial fans would have done little better. But, today's axial computer cooling fans all use impeller style blades; they develop less forward pressure than old style axial blades found on box fans, and far less pressure than a squirrel cage fan.
      What they do develop very well is a swirling output. When you mount an impeller blade at the entrance to a funnel, air swirl begins before the air even starts its journey down the funnel to the mixing tube entrance.
      As we all know, there "ain't no free lunch." All this wonderful vorticity comes at a price; in fact the fan barely puts out any positive air pressure at all, once it comes out the small end of the funnel, and enters the mixing tube.
      Note: Back pressure from the funnel restriction is so much greater than the remaining forward pressure that you must light the burner before you even start the fan running, or you just might shoot a flame out through that poor plastic fan, instead of out the flame nozzle, where it belongs! This is even true of a properly constructed burner, let alone a burner where stubborn people break all the safety rules, just because they can, and "nobody is the boss of them." All who read this; consider yourself warned.
      It takes both the venturi and flame nozzle dynamics operating IN A PROPERLY CONSTRUCTED BURNER to overcome back pressure, and keep the fuel gas flowing forward; not sucked out through the fan.
      Now, for the good news. A Vortex burner provides high speed very low pressure gas/air flow to the flame nozzle, allowing the operator to turn it up higher than any other homemade burner design, while maintaining a single wave front neutral flame. You can also build the smallest stable burners, and run them up far higher than even my own high-speed tube burners.
      Why??? Because, Vortex burners provide a much faster gas/air flow into the flame nozzle at much lower pressures than any other homemade design, allowing you to turn up a burner far higher for any given nozzle diameter than other burners. Every feature on these burners is designed either to produce the strongest vortical flow, or to make the best use of that flow.
      Sounds too good to be true? Looky here: The main purpose of a flame nozzle on the end of your burner's mixing tube is to create a low pressure area behind the flame. The difference between ambient air pressure (the air surrounding the flame on all sides other than the nozzle it is coming out of) and the pressure of a nozzle's air/gas output, is what keeps the flame "glued" to the end of the burner, rather than being blown out. The more you can lower the pressure of the air/gas mixture entering that nozzle the more push from combustion can be contained. Alas, just about everything you can do to increase mixture flow speed also increases flow pressure. Thus, the wonderfulness of vorticity. Ain't life grand?
      Hmmm; if it's sooo darned good how come nobody did it before, huh? Well, impeller style blades on axial computer fans haven't been around all that long, or someone else would have. I tried them in the first place because squirrel cage fans were more bother to install on venturi burners than their problematic performance justified.
      Thus we come to that famous old saying: "I may be slow but I'm ahead of you," which, when placed on the back of slow trailers, has ended quite badly for someCool
      Mikey
      ----- Original Message -----
      From: StoneTool owly@... [hobbicast] <hobbicast@yahoogroups.com>
      To: hobbicast@yahoogroups.com
      Sent: Tue, 24 Jun 2014 13:55:34 -0000 (UTC)
      Subject: Re: [hobbicast] Mikey re Vortex Burner
       
      Mikey:
          I don't understand...........     Is the "vortex burner" a
      different critter?

                                                                     
                                          Howard

      On 06/23/2014 10:47 PM, michael.a.porter@... [hobbicast]
      wrote:
      No, no, Howard:
      You don't understand; this is another trip down to the deep
      end of the pool Innocent
      Mikey
      ----- Original Message -----
      From: StoneTool owly@... [hobbicast]
      <hobbicast@yahoogroups.com>
      To: hobbicast@yahoogroups.com
      Sent: Tue, 24 Jun 2014 00:10:21 -0000 (UTC)
      Subject: Re: [hobbicast] Mikey re Vortex Burner
       
      I've built 5 of your
      burners.........the larger ones, and they work
      great............
      Thanks for a good design and a good book!

                                                             
             
                              Howard

      On 06/23/2014 11:07 AM, michael.a.porter@...
      [hobbicast]
      wrote:
      Lance,
      I had zero luck opening the video because: One, I'm
      an
      ignorant old metal worker who needed night classes just
      to use a
      computer at all, and; two, I wasted about two grand on a
      brand
      new computer with a Windows Eight operating system. Do
      you know
      what single virtue Eight has? It makes Vista look good
      in
      comparison! I don't really need to see the videos,
      because your
      description tells me all that seeing the videos would.
      Only
      videos of working burners tell much of value; then, I
      can see if
      something needs a little tweaking, or if the burner is
      already
      set perfectly.
      I have changed a few things on this burner:
      (1) I'm using a 1/4" copper tube, because it allows
      anyone to
      solder a MIG contact tip in place, and provides a better
      gas
      feed.
      (2) The plate thickness is upped to 3/8" because it
      can be
      ordered as flat bar, which is much cheaper than plate.
      Your burner's symptoms sound very much like lack of
      gas volume
      to the burner, which puts you in a "catch twenty
      two";
      lower pressure just aggravates the problem, but trying
      to
      overcome the lack of volume with feed higher pressure
      will over
      accelerate the gas molecules, messing up proper mixing.
      The problem is that so many things, or combination of
      things,
      which won't be obvious to see in a video, can cause your
      problems (ex. a bit of solder where it doesn't belong in
      the gas
      feed, or some other constriction; nozzle overhang not
      set right;
      poor seal, or obstruction in fan to mounting plate, or
      mounting
      plate to funnel opening).
      We will either have to go over every single detail
      (with
      photos) by email, or I'll need to check the burner out
      "hands
      on." I know that mailing it is expensive and
      inconvenient;
      reworking a burner isn't cheap or easy for me either; I
      don't
      make the offer lightly.
      Either solution might be a lot of work for both of
      us; on the
      other hand, have you had a better offer lately?
      My wife will be home from Europe next week, and with
      her help
      I can get a video of my own 1" Vortex burner running. My
      buddy
      Gene should be back from his RV road trip in time to
      help me
      make a video, if she can't help enough. That doesn't
      mean such a
      video will necessarily  do you any good. Mostly, it will
      prove
      that the burner design does work, but that is no help in
      pinpointing some particular problem, which may not be
      obvious.
      Things are actually much better for you than they
      seem,
      because when a burner is running so badly, the solution
      is
      usually a simple fix; isn't that ironic? It's the
      burners that
      are running weakly that usually need a complete rebuild
      (or a
      trash can).
      Mikey


      The

      shallow bell and the deeper bell you sent will
      not

      light, even at 15 psi gas pressure.
      Their

      video is on Google drive. The flame is burning
      back into

      the mixing tube.

       

      Tonight I got the custom made bell to light
      at 5

      psi, but the flame is weak

      and very yellow even up to 15 psi. The fan
      is

      running full tilt, but the flame

      appears to be oxygen starved. 

       

      With my venturi aspirated burners, I run
      about 8

      psi with no trouble.

      What are the parameters with the vortex?

       

      Where is a good place to upload the videos
      so you

      can see what's happening?

       


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