That being said, I'm just an interested nerd, who's also waiting for Tdacer to expand on, and fix any inaccuracies. For one, I think it might be that the design condition has the air coming from straight ahead (the slug of air that enters the inlet has the same diameter as it does far ahead before any disturbance) while the expanding flow is at a speed faster than design. And the primary reason the inlet expands is to slow down the air and increase its pressure. And I'm wondering how this interacts with the "matching" of the airflow field at the lip I mentioned earlier.