Fan air flow

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

  1. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    Ok I did it... Well I tried it...
    Here is the result:
    Flow1.PNG Flow2.PNG
     
    Mike Kelly and mike01hu like this.
  2. Irawan Tri Kusumo

    Irawan Tri Kusumo Well-Known Member

    Joined:
    Sep 5, 2015
    Messages:
    116
    Likes Received:
    21
  3. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
  4. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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

    Joined:
    Sep 4, 2015
    Messages:
    106
    Likes Received:
    21
    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

    Joined:
    Oct 7, 2015
    Messages:
    944
    Likes Received:
    190
  7. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    Ya its a long way to master it... All simulation tools are...
     
  8. wahatever

    wahatever Member

    Joined:
    Sep 6, 2015
    Messages:
    14
    Likes Received:
    3
    A silly question. Will it not be a higher airflow to the right extruder than for the left one?
     
  9. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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...
     
    wahatever likes this.
  10. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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:

    Chase.Wichert likes this.
  15. mike01hu

    mike01hu Well-Known Member

    Joined:
    Apr 22, 2014
    Messages:
    957
    Likes Received:
    167
    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

    Joined:
    Mar 1, 2016
    Messages:
    775
    Likes Received:
    208
    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.
     
    mike01hu likes this.
  17. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    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

    Joined:
    Mar 1, 2016
    Messages:
    775
    Likes Received:
    208
    Flow diverters I'll add some
     
  19. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,411
    Likes Received:
    735
    And the next one...
     

    Attached Files:

  20. mike01hu

    mike01hu Well-Known Member

    Joined:
    Apr 22, 2014
    Messages:
    957
    Likes Received:
    167
    That puts a different perspective on it. The flow from the rear appears too strong.

    I off to bed!
     

Share This Page