How does inlet distortion affect compressor performance?

• A. Causes uneven airflow, reduces surge margin, increases vibration and potential stall.
• B. Improves efficiency.
• C. No effect.
• D. Only affects turbines.

Answer: (A)

Inlet distortion introduces nonuniform flow into the compressor. When the air entering the compressor isn’t evenly distributed, different rows and passages see different velocities and possibly swirl. This causes uneven blade loading across the compressor rotor, which increases aerodynamic losses and reduces the overall pressure rise the stage can sustain. The nonuniform flow pushes the operating point toward the unstable region of the compressor map, decreasing surge margin. It also can trigger local flow separation and stall on some blades, and the unsteady forces generated by these effects raise vibration levels. This combination—uneven airflow, lower surge margin, and increased likelihood of stall and vibration—is why inlet distortion degrades compressor performance.