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Energy of a water 'fan'

  1. Oct 24, 2007 #1
    How would you go about calculating the energy required to propel water through a circular-type blade at 3 metres per second??

  2. jcsd
  3. Oct 24, 2007 #2
    in this case you would be calculating power (energy per time)

    think about how much mass is moving, and how fast it is going.

    then use the equation for kinetic energy.

    bear in mind, that this is the MINIMUM amount of power required, since it is assumes 100% conversion of propeller work to kinetic energy. The actual number is much greater and difficult to predict.

    It is probably only estimable by using correlations based on the reynold's number and propeller design.
  4. Oct 24, 2007 #3


    User Avatar

    Staff: Mentor

    Obviously it depends on the device, but you can figure 50-75% efficiency for a pump or propeller.
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