Overall efficiency of a reaction turbine: choose the correct ratio Define the <strong>overall efficiency</strong> (η<sub>overall</sub>) for a reaction turbine in terms of power and available hydraulic energy. Choose the correct expression.
Mechanical Engineering
Hydraulic Machines
Difficulty: Easy
Choose an option
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APower produced by the turbine ÷ energy actually supplied by the turbine (ρ g Q H)
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BActual work at the turbine ÷ energy imparted to the wheel
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CWork done on the wheel ÷ energy (head) actually supplied to the turbine
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DNone of the above
Answer
Correct Answer: Power produced by the turbine ÷ energy actually supplied by the turbine (ρ g Q H)
Explanation
DefinitionsOverall efficiency ηoverall = Shaft power / Hydraulic power from head = Pshaft ÷ (ρ g Q H).Hydraulic efficiency = Runner (wheel) power ÷ ρ g Q H.Mechanical efficiency = Shaft power ÷ Runner power.
Option mapping(a) matches overall efficiency.(b) matches mechanical efficiency.(c) matches hydraulic efficiency.
Final AnswerPower produced by the turbine ÷ energy actually supplied by the turbine (ρ g Q H).