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Fluid flow through tiny hole

  1. Dec 31, 2009 #1
    I would like to calculate the rate at which fluid(oil) is transferred from one chamber to the other.
    Note the orifices is in the range of 0.0030 to 0.0760 in i'm wondering if the very small size of this hole requires any special consideration.

    http://myimgs.net/images/oyfi.jpg [Broken]

    I realize more info such as oil density and dimensions are required for a exact solution, however I would like to determine a general solution into which I can substitute these values.
    Any hints to get me on the correct path or even better a sample calculation would appreciated.

    Note this is not a homework question.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Dec 31, 2009 #2
    You might consider the type of flow to be expected for oil flowing through the small diameter hole using the definition of Reynolds number and the physical properties of the type of oil considered. If Re < 2300 flow is laminar, above it is expected to be turbulent.
    Go on from this point.
  4. Dec 31, 2009 #3


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    ASME MFC-14 handles flow through small orifi but I am thinking that this is even too small for that. I have a copy at my desk which I don't have access to right now. That being said, the flow will still follow orifice equations. The tough part is to find out what the Cd of the small orifice is, especially with what will be pretty small Re.
  5. Dec 31, 2009 #4
    I suppose a real experiment would not be difficult to set up: pressurized reservoir, small orifice and weighing scale (to measure output flow) On the other hand, there must have been done extensive research on flow of viscous substances through small holes if one considers automated dispensers for glues, hot melts etc
  6. Dec 31, 2009 #5
    I'm confused about the setup. Is chamber #2 initially full of air? I would expect air bubbles to form at the orifice and rise to the top of chamber #1. Not a simple problem at all.
  7. Jan 1, 2010 #6
    Both chambers are full of oil, single fluid problem, no air involved. also the spring is weak so we will assume the flow to be very slow.

    happy new years everyone
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