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Homework Help: Bernoulli equation problem

  1. Mar 17, 2010 #1
    1. The problem statement, all variables and given/known data
    An open tank of water is sited on top of a hill and has a pipe leading from the bottom leading down to a vertical water fountain. The base of the tank is 15m above the fountain nozzle and the depth of water in the tank is 1.0m.

    1. Draw a ruled sketch of the system, showing the levels above datum of each significant point.

    2. For the case of the blocked nozzle with no flow, calculate the static, potential and total pressures at three significant points. Tabulate your results.

    3. The nozzle is then unblocked and a vertical fountain is produced. Assuming that the velocity of water in the pipe is small compared to that from the nozzle and that that friction losses are small, calculate the discharge velocity and also the height to which the jet will reach.

    4. A throttling valve is introduced into the pipe and is used to control the height of the fountain jet. Calculate the static pressure drop across the valve needed to give a fountain jet height of 5.0m and the velocity at the nozzle.

    2. Relevant equations

    3. The attempt at a solution
    Hi there i seem to be finding no.3 and 4 a bit tricky to solve!

    For no.3 Would i use the potential energy equation and make 'h' the subject to find the height of the water jet or because the tank is subjected to atmospheric pressure would the height be around 15m which is the bottom of the water tank?

    For no.4 would i use the same equation as above or have to work out the kinetic energy first??

    If any could help would be really helpful :) Thanks
  2. jcsd
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