Keep in mind that that as additional outdoor air is added moisture loads increase.
These doors are fully open (sucked in at the rear) during takeoff to provide additional air.
With additional air, the fire consumes more fuel and burns hotter.
Once the bubble is inflated, no additional air is required.
With the additional air in the boost, more fuel can be added to the charge, and the power of the engine is increased.
The roofs are very flat, and tilted to catch additional air.
A process called inducement causes additional air from behind the fan to be drawn into the airflow.
The gas mixes with additional incoming air to provide a secondary burn.
The fire also pulls additional air, 5 to 10 times the amount required for combustion, from the room.
We do not want additional air and water pollution.