Basic fluid dynamics

  1. Hi guys and girls,

    I hope you can help an electronics engineer out of his place in the mechanical world:uhh:

    My very basic question is for a vessel holding a liquid at a given pressure and a given opening in the vessel how can i calculate exit velocity and mass flow rate? Like if i blow a balloon up to say 1 bar (good balloon huh:)) and then put a 1mm hole inside it how fast will the air be travelling as it leaves the balloon?


    I dont need anything to detailed ( not worried about internal friction losses etc) and for now i can assume the vessel is fed by constant pressure mechanism i.e it wont drop pressure as it empties!

    Any help gratefully recieved
     
  2. jcsd
  3. jbriggs444

    jbriggs444 1,847
    Science Advisor

    Ignoring friction, the exit velocity should be just enough to squirt a stream back up to the height of the surface of the fluid.

    That's about 30 feet for water at one atmosphere. 30 feet at one g is about 45 feet per second. Double the pressure and you multiply the stream velocity by sqrt(2).
     
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