Fan air flow

Discussion in 'BigBox General Chat' started by Alex9779, May 25, 2016.

  1. Alex9779

    Alex9779 Moderator
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    Ok I did it... Well I tried it...
    Here is the result:
    Flow1.PNG Flow2.PNG
     
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  2. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

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  3. Alex9779

    Alex9779 Moderator
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  4. Alex9779

    Alex9779 Moderator
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    Ok another one:
    Flow3.PNG
    This worries me a bit and shows why I have problems with corners in the front...
     
  5. corey

    corey Well-Known Member

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    I can confirm what your seeing in your sim is about as good as that fan get's, not much thought went into the fan design which is a bit strange considering this can destroy a print just as much as a badly setup printer. I have not used my bigbox since titan upgrade for this reason, I'm hoping someone with some cad skills to release a proper design that works....
     
  6. R Design

    R Design Well-Known Member

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  7. Alex9779

    Alex9779 Moderator
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    Ya its a long way to master it... All simulation tools are...
     
  8. wahatever

    wahatever Member

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    A silly question. Will it not be a higher airflow to the right extruder than for the left one?
     
  9. Alex9779

    Alex9779 Moderator
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    This could be because of the fan type I selected. The fan has a rotation direction. So on one side of the fan outlet there is a higher speed.
    I am very new to flow simulation so this is just what I expect.
    And all this should only give a small insight of how it COULD be.
    I am still working out the details of the assumptions I make, the fan I selected is way too forceful, I have to research some better numbers how much volume flow the small fans can reach and such stuff...
     
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  10. Alex9779

    Alex9779 Moderator
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    Small update: I am about to simulate @Chase.Wichert's fan shroud and because of the lack of datasheets from China I chose the smalles ebmpapst radial fan "RFL 35-8/14 N".
    I am watching the datasheet right now and I think I am going to lower the numbers then a bit for our 40x40x20 radial fan... I think I am going to take about 2/3 of the values this fan has as a starting point...
    Any objections?
     
  11. Alex9779

    Alex9779 Moderator
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    I found some values for our fans:
    • Speed: 4000-7000rpm
    • Static Pressure: 4.80-8.90mmh2o
    • Air Flow: 2.72-4.80cfm
    Since we use them with the max rated voltage of 24V I am going to use the max values and for the characteristics I compare with the one from ebmpapst and extrapolate something...
     
  12. Alex9779

    Alex9779 Moderator
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    Ok and I got the details for our fan too:
    7000RPM and 4.8cfm
    The strange thing is the static pressure, in the general info they write mmh2o as unit, in the table for the fans they have inh20 (inch) but the same numbers. his cannot be... 8.9inh2o would be over 2200 Pascal! The bigger ebmpapst fan has only about 190 Pa...
     
  13. Alex9779

    Alex9779 Moderator
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    So I just made a linear characteristics, that should be ok for the calculation... Fighting with the mesh at the moment...
     
  14. Alex9779

    Alex9779 Moderator
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    Ok here is the first result.
    I exported it as an eDrawings file, that way you can turn it around but you need eDrawings, get it from http://www.edrawingsviewer.com
     

    Attached Files:

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  15. mike01hu

    mike01hu Well-Known Member

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    That looks quite good, just a little less flow in one corner but it looks like a fair distribution.
     
  16. Chase.Wichert

    Chase.Wichert Well-Known Member

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    I can modify a little bit to get more even distribution, but it looks like the cooling might be pretty good. Maybe make the entrances to the ports closest to the fan a little smaller to direct more airflow around.
     
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  17. Alex9779

    Alex9779 Moderator
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    Ya but the outlets on the left and right side to the back side have very little flow...
     
  18. Chase.Wichert

    Chase.Wichert Well-Known Member

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    Flow diverters I'll add some
     
  19. Alex9779

    Alex9779 Moderator
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    And the next one...
     

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  20. mike01hu

    mike01hu Well-Known Member

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    That puts a different perspective on it. The flow from the rear appears too strong.

    I off to bed!
     

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