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Homework Help: Need help with flow physics

  1. Feb 12, 2007 #1


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    i need your urgent help in the following :

    I have a cylindrical tank :
    - inner diameter is 2 m
    - capacity 50 m3
    - hight over ground 0.5 m (50 cm) from ground to tank bottom

    - the tank is 60% full of liqued and 40% gas , the pressure inside
    the tank is 3 bar :

    What is the drain size (diameter) that allow to get 2.8 m3/h of the liquid , without using any pumps , just by the pressure force inside the tank ?

    and thanks for your help
    :cry: :confused:
  2. jcsd
  3. Feb 12, 2007 #2
    That is a funny tank, in practice. (16 m height / 2m dia.) Is it horizontal or vertical?

    Just go to the link below and do some trials and error.

    Consider 3 bar as 30 meters head approximately. 60% liquid adds about 9 meters and initially the head will be 39 meters. As the tank gets emptied, the head will be 30 meters. The average of these two flow readings gives you the average flowrate.

    The diameter is approximately 0.2mm

    Use a rather conservative discharge coefficient of 0.85
  4. Feb 12, 2007 #3


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    many thanks for reply

    the tank is horizontal , attached drawing is cross section in tank

    and what is the effect of liquid viscosity ?

    thanks again

    Attached Files:

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