What channels the flow of air over the exposed rotor surfaces?

The flow of air over the exposed rotor surfaces is primarily channeled by the rotor blades themselves, which are designed with specific aerodynamic shapes to optimize lift and minimize drag. Additionally, the rotor hub and any surrounding structures, such as the fuselage or rotor shrouds, can influence airflow patterns. The design and angle of attack of the blades also play a crucial role in directing airflow efficiently over the rotor surfaces.