Types of Airflow: By considering air speed, airflow are two types. They are :
- Compressible Airflow : When the airflow is passing airfoil surface & compressing every movement that means changing the density of the fluid elements from point to point. It is called compressible airflow. It is occurred on airfoil for the supersonic range speeds (Mach Number : 1.2 -5.0).
- In-compressible Airflow : Such kind of airflow is always in-compressible that means the flow is never changed or constant , when passing the airfoil surface is called in-compressible airflow. It is occurred on airfoil for the subsonic range speeds (Mach Number : less than 0.8 / 1.0).
