Question

For a flow in a duct, what is Mach number a function of?

(a) Local duct area to sonic throat area

(b) Sonic throat area to local duct area

(c) Local duct area to convergent duct area

(d) Local duct area to divergent duct area

I have been asked this question in homework.

I would like to ask this question from Nozzles in division Quasi-One-Dimensional Flow of Aerodynamics

Answer 1

Correct choice is (a) Local duct area to sonic throat area

To explain: On observing the area – Mach relation for a flow inside a duct, we notice that the Mach number at a point in a duct is a function of ratio of local duct area to the sonic throat area.

M = f(A/A^*)