Answer: Hydraulic Efficiency of a Pelton Turbine

[skpmech]

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.

 

[CWatters]

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?