GATE 2025 AE – Question 51
The mass flow rate in a supersonic wind tunnel is 2 kg/s when the stagnation pressure and stagnation temperature are 1 MPa and 800 K, respectively. If the stagnation pressure and stagnation temperature are changed to 3 MPa and 200 K, the mass flow rate in the tunnel changes to _______ kg/s (answer in integer).
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Correct answer: 12
Explanation
With the same choked throat area, the mass flow rate is $\dot m \propto \frac{p_0}{\sqrt{T_0}}$. The ratio is $\frac{3}{1}\sqrt{\frac{800}{200}} = 3 \times 2 = 6$, so $\dot m = 12$ kg/s.