Contaminant buildup on the compressor blades results in what outcome?

• A. It improves engine surge margin
• B. It causes higher fuel consumption but improves thrust
• C. It has no effect on performance
• D. It reduces engine performance by reducing blade aerodynamic efficiency

Answer: (D)

Contaminant buildup on compressor blades disrupts the smooth airflow through the compressor. The deposits create roughness and protrusions that disturb the boundary layer, causing earlier flow transition and increased drag on the blades. This reduces the effective airfoil performance, so each stage delivers less pressure rise and the overall pressure ratio falls. With degraded compression, the engine’s thrust capability drops and fuel consumption tends to rise for the same operating point. It also lowers surge margin and raises the risk of compressor stall. So the outcome is a reduction in engine performance due to decreased blade aerodynamic efficiency.