Which statement describes an axial compressor?

Which statement describes an axial compressor?

• A. Air flows in a straight line through rotating and stationary blades
• B. It uses a single impeller at the center
• C. It relies on centrifugal diffusion to raise pressure
• D. It compresses air through magnetic fields

Answer: (B)

In an axial compressor, air is pushed along the axis of the machine through a stack of rotating blades (rotors) and stationary blades (stators) arranged in stages. The flow stays essentially parallel to the axis as each stage adds energy and then diffuses the air to the next stage. This is why axial compressors achieve high flow with multiple stages to boost pressure gradually. The description about a single impeller at the center corresponds to a centrifugal (radial) compressor, where air enters at or near the center and is flung outward by the impeller, with pressure rising through centrifugal diffusion in a diffuser. That radial, center-entry design is not axial. The other options either describe diffusion in a centrifugal context or rely on concepts (like magnetic fields) that aren’t how aircraft engine compressors operate.

In an axial compressor, air is pushed along the axis of the machine through a stack of rotating blades (rotors) and stationary blades (stators) arranged in stages. The flow stays essentially parallel to the axis as each stage adds energy and then diffuses the air to the next stage. This is why axial compressors achieve high flow with multiple stages to boost pressure gradually.

The description about a single impeller at the center corresponds to a centrifugal (radial) compressor, where air enters at or near the center and is flung outward by the impeller, with pressure rising through centrifugal diffusion in a diffuser. That radial, center-entry design is not axial.

The other options either describe diffusion in a centrifugal context or rely on concepts (like magnetic fields) that aren’t how aircraft engine compressors operate.