The GATE Grind

GATE 2019 AE – Question 47

Aerodynamics · Compressible flows: isentropic flow, normal and oblique shocks, Prandtl-Meyer flow, nozzles and diffusers · 2 marks · Numerical answer

Across a stationary normal shock, $p_2/p_1=1+[2\gamma/(\gamma+1)](M_1^2-1)$. Upstream air has speed 800 m/s, static temperature 300 K and pressure 1 atm. With γ=1.4 and R=287 J/(kg K), find downstream static pressure in atm (two decimal places).

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: 5.95 to 6.10

Explanation

$M_1^2=V_1^2/(\gamma RT_1)=640000/(1.4\times287\times300)=5.3094$. Substitute into the given shock relation: $p_2/p_1=1+(2.8/2.4)(5.3094-1)=6.0276$. Since p₁=1 atm, p₂=6.03 atm.

More Compressible flows: isentropic flow, normal and oblique shocks, Prandtl-Meyer flow, nozzles and diffusers questions

All Compressible flows: isentropic flow, normal and oblique shocks, Prandtl-Meyer flow, nozzles and diffusers questions →