I understand Bernoulli's Principle at different sections of the wind tunnel (static and dynamic pressure), and that it is equal to the atmospheric pressure (hence open-circuit). However, I don't really understand why the stagnation pressure inside the wind tunnel doesn't change at each section.
I can sort of understand why we set the constant equal to the atmospheric pressure (because air is being sucked in and blown out at that pressure?), however, I don't really get (conceptually) why the stagnation pressure is constant through the wind tunnel.
