Correct Answer - Option 1 : Mechanical efficiency
Explanation:
Mechanical Efficiency:
It is the ratio of the power delivered by water to the runner of a turbine and the power transmitted to the shaft of turbine. Due to mechanical losses, the power available at the shaft of the turbine is less than the power delivered.
\(\eta_m~=~\frac{shaft~power}{brake~power}\)
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Hydraulic Efficiency: It is defined as the ratio of power given by water to the runner of turbine to the power supplied by the water at the inlet of turbine.
The power at the inlet of the turbine is more and this power goes on decreasing as the water flows over the vanes of the turbine due to hydraulic loses as the vanes are not smooth.Hence, power delivered to the runner will be less than the power available at the inlet of the turbine.
\({\eta _h} = \frac{{power\;delivered\;to\;runner}}{{Power\;supplied\;at\;inlet}}\)
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Overall Efficiency: It is defined as the ratio of power available at the shaft of the turbine to the power supplied by the water at the inlet of the turbine.
\({\eta _o} = {\eta _h} \times {\eta _m}\)