Question

To refrain from separation in subsonic nozzles, the expansion angle must not be more than _____

(a) 10 degrees

(b) 20 degrees

(c) 30 degrees

(d) 40 degrees

This question was posed to me in unit test.

My question is based upon Flow through Nozzles in section Flow Through Pipes of Fluid Mechanics

Answer 1

Right answer is (a) 10 degrees

Explanation: If the angle is more than 10 degrees, there will be a drift amidst the nozzle. At any angle more than 10 degrees, this separation will occur. But the minimum value is 10 degrees. So, the answer is 10 degrees.