From Sutton chapter 3 he uses this figure to describe the ratios of pressure//area//temperature as functions of Mach Number.
I know that we are bringing the fluid to an adiabatic "stop" through expansion which explains the drops in pressure and temperature. However, what I am having trouble understanding is why once we hit the throat at M=1, why the pressure and temperature continue to decrease.
Here's the relation for the area ratio:
Does this have to do with the stagnation conditions or? This is my first time dealing with compressible flow as my thermodynamics class did not cover this material.