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GATE 2020 ME (ME2) – Question 28

Thermal Engineering Applications · Turbomachinery: turbines, compressors, pumps · 1 mark · Multiple choice

In a hydraulic turbomachine stage, h₁ is enthalpy at stator inlet, h₂ at stator outlet (rotor inlet), and h₃ at rotor outlet. If h₂ − h₁ = h₃ − h₂, find the degree of reaction.

  1. zero
  2. 50%
  3. 75%
  4. 100%

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Correct answer: (B) 50%

Explanation

Reaction is rotor static-enthalpy change divided by total stage static-enthalpy change. The given relation makes stator and rotor changes equal, so R=(h3−h2)/[(h2−h1)+(h3−h2)]=1/2. **Answer:50%,B**.