Which statement describes how an axial flow compressor operates?

• A. Air enters stages of rotor and stator blades, which increase kinetic energy
• B. Air enters perpendicular to the axis of rotation
• C. Kinetic energy is converted into velocity
• D. Air is compressed mainly by a diffuser without moving blades

Answer: (A)

In an axial flow compressor, each stage uses rotor blades to add energy to the incoming air, increasing its kinetic energy, and then stator blades to guide the flow and convert that kinetic energy into higher pressure for the next stage. The statement describing air entering stages of rotor and stator blades, with energy added to the flow, best captures how this type of compressor works because the moving blades do the work that increases the flow’s energy, while the stators shape and diffuse the flow to raise stagnation and static pressure as you move through successive stages.

Perpendicular entry isn’t how axial compressors operate—the air travels along the axis. The idea that kinetic energy becomes velocity isn’t accurate for a compressor, which aims to increase pressure, not just speed. And relying mainly on a diffuser without moving blades would not provide the energy input needed to compress the air through multiple stages.