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Calculate HP for this Turbine

what can increase the HP

Poll closed Dec 2, 2012.
  1. Blade length

    0 vote(s)
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  2. Force on blades

    0 vote(s)
    0.0%
  3. RPM

    0 vote(s)
    0.0%
  4. number of blades

    0 vote(s)
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Multiple votes are allowed.
  1. Nov 27, 2012 #1
    Hi Friends,

    Can someone help me find the Torque / RPM and HP from the following figures

    Turbine Blade Radius = 10 Meters
    Number of Blades = 3
    Force on each blade = 351328 Newton Meters

    This is my working.

    Torque = 10539850 Newton Meters
    RPM = Cant Find ???

    If i assume RPM as 10; HP=20058

    If 1HP=746watts

    This Turbine = 14963009watts = 14.9 Megawatts

    Am I wrong anywhere ??? Please help
     
  2. jcsd
  3. Nov 27, 2012 #2

    russ_watters

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    You can't just assume the rpm and the torque will drop as the rpm rises.

    What is the power source of the turbine.
     
  4. Nov 27, 2012 #3

    CWatters

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    There isn't enough information in the question to calculate the power or rpm.

    Power (in Watts) = Torque (in Newton meters) * Angular velocity (in Radians/second)

    You appear to be missing the Angular velocity which can be calculated from the r.p.m.
     
  5. Nov 27, 2012 #4

    AlephZero

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    What CWatters said, plus: 351328 Newton Meters is already a torque.

    Even if it was a force (the number is improbably large for a 10m turbine blade), comverting to a torque by multiplying by the blade radius (10m) would be wrong, because all force does not act at the blade tip.

    Maybe the question really said "10 RPM" but you misunderstood it as "Radius 10 Meters"?
     
  6. Nov 27, 2012 #5
    Thanks for the feedback,

    The force acting on the blades has been given after calculating the losses. Hence the figure is correct

    Force on each blade = 351328 Newton Meters
    Total blades = 3
    Net Force = 351328*3 = 10539850 Newton Meters
    The blades arm is 10 Meters

    What is the right way to calculate Torque & angular velocity with the given force and arm radius?

    Thanks
    Dilip
     
  7. Nov 28, 2012 #6

    mfb

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    You cannot calculate torque just based on force and the total size of the object, you would need the force distribution on the blades.

    In addition, your "forces" have the unit of a torque, which cannot be right.
     
  8. Nov 28, 2012 #7

    russ_watters

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    With 10m blades, that makes this a wind turbine, right? How fast is the wind moving?
     
  9. Nov 28, 2012 #8
    Sorry, my mistake

    Force on each blade is 79128 pounds, so when converted to Newtons its is 79128*4.44=351328 Newtons

    There are 3 blades with arm length of 10 meters.

    How can I calculate the angular velocity / torque / power ?

    Thanks
    Dilip
     
  10. Nov 28, 2012 #9
    Since you already have the total torque, you need the moment of inertia of the turbine and I think other resistance to rotation will be small in comparison so could be ignored for an estimate.

    Edit :whoops missed that last post. You will still need the moment of inertia.
     
  11. Nov 28, 2012 #10

    mfb

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    You don't need the moment of inertia.

    You could make some assumption where the force acts (e. g. "everything at ~5m radius", "everything at 10m radius" or "uniform distribution over the area", but it is unclear how good those approximations are. Without those assumptions, you cannot calculate the torque.

    You cannot calculate the angular velocity or power just from the force or torque.
     
  12. Nov 28, 2012 #11

    russ_watters

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    I'm sorry, but it cannot be done and repeating the question won't change that.
     
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