The overall efficiency of turbine is the ratio of
- APower delivered to runner to the power supplied at inlet.
- BPower at the shaft of the turbine to the power delivered by water to the runner
- CPower available at the shaft of the turbine to the power supplied by the water at the inlet of the turbine.Correct
- DNone of the above
Solution
Concept
Overall efficiency definition of hydraulic turbine
Formula
NONE
Step-by-step solution
1. Overall efficiency of a hydraulic turbine accounts for hydraulic, mechanical, and volumetric losses. 2. It is defined as the ratio of useful power output to total power input. 3. Power output is the shaft power available at the turbine shaft, while power input is the water power available at the turbine inlet. Answer: C
Explanation
Overall efficiency accounts for all hydraulic, mechanical, and volumetric losses experienced throughout a hydraulic turbine. It is defined as the ratio of actual mechanical power available at the turbine shaft to the total hydraulic power supplied by water at the inlet. This metric measures how effectively the hydraulic energy of fluid is converted into useful shaft work.
Why the other options are wrong
A) The ratio of power delivered to the runner to power supplied at the inlet is hydraulic efficiency. B) The ratio of shaft power to runner power is mechanical efficiency. D) Option C is the correct definition of overall efficiency.
Shortcut
Overall efficiency of a turbine = Shaft output power / Water inlet power.
Common mistake
Confusing overall efficiency with mechanical efficiency or hydraulic efficiency.
Correct answer: C) Power available at the shaft of the turbine to the power supplied by the water at the inlet of the turbine.