What supplies cooling air to the heat exchanger after takeoff?

The ram air inlet is responsible for supplying cooling air to the heat exchanger after takeoff. This system works by utilizing the forward motion of the aircraft to draw in external air, which is then directed to the heat exchanger. The process ensures that the heat generated by the aircraft's systems, particularly during takeoff and climb, is effectively managed.

The ram air inlet is particularly advantageous during high-speed flight, as it relies on the airflow generated by the aircraft's speed rather than mechanical means, making it an efficient cooling solution. The other options, while related to air management in the aircraft, do not specifically focus on providing cooling air to the heat exchanger in the context mentioned.