The reservoir pressure of a supersonic wind tunnel is 5 atm. A static pressure probe is moved along the centerline of the nozzle, taking measurements at various stations. For these probe measurements, calculate the local Mach number and area ratio: a. 4 atm; b. 2.64 atm; c. 0.5 atm.

Answer

Given,

Reservoir pressure of a supersonic wind tunnel = 5 atm

Local Mach number = ?

Area ration = ?

a) 4 atm.

  Pressure ratio =

                         = 0.8

From Isentropic Flow Tables

  M = 0.58   A/A* = 1.213

b) 2.64 atm

  Pressure ratio =

                         = 0.528

From Isentropic Flow Tables

  M = 1  A/A* = 1

c)  0.5 atm

  Pressure ratio =

                         = 0.1

From Isentropic Flow Tables

  M =2.10   A/A* = 1.8369