Test: Efficiencies of a Turbine - Civil Engineering (CE) MCQ

Hydraulic efficiency is defined as ratio between power given by water to runner of turbine and to the power supplied by water at inlet of the turbine.

Due to mechanical losses, power available at shaft of turbine is less than power delivered to the runner of turbine. Hence ratio of power at the shaft of turbine and power delivered by water to runner is known as mechanical efficiency.

Kaplan is inward flow reaction turbine and is operated under head less than 60 meters. The vanes attached to hub are adjustable and Kaplan is mainly operated in location where large quantity of water at low head is available.

Overall efficiency is defined as ratio of power available at shaft of turbine to power supplied at the inlet of turbine which is also product of mechanical and hydraulic efficiency. Its expression is given by p/(k x g x q x h) where k is density of liquid.

 Hydraulic efficiency is defined as ratio between power given by water to runner of turbine and to the power supplied by water at inlet of the turbine. This efficiency will be maximum when differentiating it with “u” and it is obtained as u = v/2.

Overall efficiency is defined as ratio of power available at shaft of turbine to power supplied at the inlet of turbine which is also product of mechanical and hydraulic efficiency.

Electrical efficiency is ratio of work output and electrical power input to electrical machine but turbine is a hydraulic machine which consists of only mechanical, volumetric and hydraulic efficiencies.

Overall efficiency is defined as ratio of power available at shaft of turbine to power supplied at the inlet of turbine which is also product of mechanical and hydraulic efficiency.

Volumetric efficiency is ratio between volume of water actually striking the runner of turbine and volume of water supplied to the turbine.

Hydraulic efficiency is defined as ratio between power given by water to runner of turbine and to the power supplied by water at inlet of the turbine. Its maximum value is obtained by replacing u=v/2 and it is (1+cos k)/2 where k is outlet blade angle.