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Shaft analysis, under water

  1. Apr 6, 2010 #1
    I am designing a fan blade which is attached to a generator. The unit will be submerged in water. The blade will be attached to the generator by a shaft. The device is semi-enclosed in a cylinder with the top and bottom open. The force of the waves will cause the propellor to spin.

    My question is: What types of forces will present on the shaft. I can think of the weight of the propellor and the torque caused by it spinning. Would the weight of the propellor be neglected since it is submerged underwater? Any response is appreciated. Thank you.
  2. jcsd
  3. Apr 6, 2010 #2
    A diagram and better description would help. It's not clear exactly how this is working. One thing is easy to answer, however. The weight of the propeller can't be neglected unless it is neutrally buoyant which is unlikely. There will be hydrodynamic forces present on the blade and shaft, if you are in waves. Are the waves crashing (on the device) or not?

    How carefully have you designed this system? Is this an intuitive guess, or a truly novel system that has been studied in detail? If the latter, then I can see why you don't give details, but if you want help, it's best to give at least some details. Your description of wave power doesn't sound like it will work well. However, without a diagram it's difficult to be sure.
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