Which assembly directs airflow to the first stage compressor blades?

Which assembly directs airflow to the first stage compressor blades?

• A. Air inlet vein
• B. Inlet duct
• C. Diffuser
• D. Turbine nozzle

Answer: (A)

Directing the air into the first-stage blades requires controlling its angle and distribution right at the entry. This is the job of the air inlet vane (inlet guide vane), which shapes and aligns the incoming flow so it meets the first compressor stage at the correct incidence and with a uniform velocity profile. Properly angled air reduces flow separation and swirl, improving efficiency and stall margin for the entire compressor. The other assemblies serve different roles: the inlet duct simply carries air from the outside toward the engine but doesn’t set the blade incidence; the diffuser downstream helps recover pressure after entry but doesn’t direct the flow into the first-stage blades; and the turbine nozzle directs hot combustion gas onto turbine blades, not the compressor intake.

Directing the air into the first-stage blades requires controlling its angle and distribution right at the entry. This is the job of the air inlet vane (inlet guide vane), which shapes and aligns the incoming flow so it meets the first compressor stage at the correct incidence and with a uniform velocity profile. Properly angled air reduces flow separation and swirl, improving efficiency and stall margin for the entire compressor.

The other assemblies serve different roles: the inlet duct simply carries air from the outside toward the engine but doesn’t set the blade incidence; the diffuser downstream helps recover pressure after entry but doesn’t direct the flow into the first-stage blades; and the turbine nozzle directs hot combustion gas onto turbine blades, not the compressor intake.