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Homework Help: Question about turbine

  1. Sep 19, 2014 #1
    The hydraulic efficiency of a turbine (let pelton turbine) is given by - (power developed by runner or shaft power)/(water power)

    shaft power is - (mass flow rate)*(Vw1+Vw2)*u

    water power is - density*g*Q*H

    My question is that the pressure head is converted into kinetic energy in nozzle then we should use water power = 0.5*m*V^2
    why we use that formula.

    my teacher said that energy input to runner= 0.5*m*V^2
    and energy input to whole turbine system = density*g*Q*H
    please explain.
  2. jcsd
  3. Sep 20, 2014 #2


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    Not sure I follow your question but..

    density*g*Q*H ... That looks like the equation for the theoretical power available from something like a dam. It depends on the density, gravity, height and flow rate. Presumably Q is the flow rate?

    The KE of a mass m coming out of the pipe will be 0.5*m*V^2 but power = energy/time. So is m the mass or flow rate?
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