What is the flat surface with cooling holes that forms the after edge of the blade airfoil?

The trailing edge of the blade airfoil is the flat surface where the airflow exits from around the blade, and it typically features cooling holes. This design is crucial for the performance and efficiency of gas turbine blades as it helps in managing the temperature and cooling of the blade, especially in high-performance applications. The trailing edge plays a key role in the aerodynamic shape of the blade, influencing both lift and drag, and hence impacts the overall efficiency of the gas turbine engine.

The other choices refer to different parts of the blade: the leading edge is located at the front where the air first contacts the blade, the tip is the uppermost part where the blade meets the air above, and the root is the section of the blade that connects to the turbine disk. Each of these regions has distinct functions and attributes that are essential for the operational effectiveness of gas turbine blades.