GATE 2016 ME (ME1) – Question 28
Consider two hydraulic turbines having identical specific speed and effective head at the inlet. If the speed ratio (N1/N2) of the two turbines is 2, then the respective power ratio (P1/P2) is _____________
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 0.24 to 0.26
Explanation
Turbine specific speed scales as Ns=N sqrtP/H^(5/4). Equal Ns and H require N1sqrtP1=N2sqrtP2. Squaring gives P1/P2=(N2/N1)²=(1/2)²=**0.25**. The power ratio is inverse-square in the speed ratio for this comparison.