GATE 2025 AE – Question 34
The lift per unit span for a spinning circular cylinder in a potential flow is 6 N/m. The free-stream velocity is 30 m/s, and the density of air is 1.225 kg/m$^3$. The circulation around the cylinder is ____ m$^2$/s (rounded off to two decimal places).
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Correct answer: 0.15 to 0.17
Explanation
By the Kutta-Joukowski theorem $L' = \rho V_\infty \Gamma$, so $\Gamma = \frac{6}{1.225 \times 30} = 0.163$ m$^2$/s.