So I'm reading the Gas Turbine Engine Fundamental, and suddenly come across the airflow passes through one axial compressor stage. I wonder why the Resultant Rotor Inlet Velocity is pointing downward, while the Rotor Speed vector is pointing upward. The Resultant Rotor Inlet Velocity is the sum of two vectors Air Inlet Velocity and Rotor Speed. The Resultant Rotor Inlet Velocity is supposed to pointing upward right ??
The same thing happen the rotation direction is downward, why would the Resultant vector pointing upward ??
Can anyone explain for me plz ? Its really confuse me to be honest.