GATE 2021 CE (CE2) – Question 59
An ideal vertical venturimeter has inlet diameter 20 cm, throat diameter 10 cm and tap separation 30 cm. A mercury differential manometer reads 15 cm, SG=13.6. With g=9.8, find flow in L/s to two decimals.
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Correct answer: 49 to 50
Explanation
The pressure-plus-elevation head difference is $h=(13.6-1)(0.15)=1.89$ m of water. The tap elevation difference is already accounted for by differential-manometer hydrostatics. Ideal flow is $Q=A_t\sqrt{2gh/[1-(d_t/d_1)^4]}=0.0493700$ m³/s, or **49.37 L/s**.