Question

In which scenario is the throat area of both the nozzle and diffuser the same?

(a) Ideal isentropic diffuser

(b) Ideal adiabatic diffuser

(c) Ideal isobaric diffuser

(d) Ideal Isochoric diffuser

I got this question in semester exam.

I want to ask this question from Supersonic Wind Tunnels in division Compressible Flow through Nozzles, Diffusers and Wind Tunnels of Aerodynamics

Answer 1

Right answer is (a) Ideal isentropic diffuser

To explain: In case of ideal isentropic diffuser the total pressure remains constant. Thus from the relation between the throat area and total pressure we see that p01 = p02 = constant. Hence the throat areas At2 = At1. It is important to note that ideal isentropic diffuser is a hypothetical case and is not possible to achieve in real life.

\(\frac {A_{t2}}{A_{t1}} = \frac {p_{01}}{p_{02}}\)