What is the primary purpose of the variable guide vanes?

• A. To prevent compressor stalls
• B. To increase thrust
• C. To reduce fuel consumption
• D. To adjust exhaust temperature

Answer: (A)

Variable guide vanes adjust the angle of the stator blades in the compressor to keep the airflow entering the rotor at the proper angle as operating conditions change. This keeps the flow smooth and prevents flow separation that can lead to compressor stall or surge, especially during throttle changes or low-speed/high-pressure-ratio situations. By maintaining stable airflow through the compressor, they protect engine stability and allow reliable operation across a wide range of speeds and power settings. While smoother airflow can support overall performance, the primary purpose is to prevent stalls, not to directly increase thrust, reduce fuel consumption, or adjust exhaust temperature.