Question

What happens to the velocity of the supersonic flow in the divergent duct?

(a) Decreases

(b) Increases

(c) Remains the same

(d) Changes periodically

The question was posed to me in examination.

My question comes from Governing Equations for Quasi One Dimensional Flow in division Compressible Flow through Nozzles, Diffusers and Wind Tunnels of Aerodynamics

Answer 1

Correct option is (b) Increases

Best explanation: Supersonic flows have M > 1 which results in M^2 – 1 value in the area – velocity relation to be positive. Thus for divergent sections where cross – sectional area increases with x, the value of velocity increases.