🔍 Key Concepts

• How compressor surge occurs in a gas turbine (relationship between airflow and compressor pressure ratio) • Which components can directly change compressor airflow characteristics versus those that only control fuel or temperature • The purpose of variable stator vanes in axial-flow compressors

💭 Think About

• Which option actually changes the aerodynamic conditions inside the compressor to prevent the air from stalling or flowing backward? • Which options only react by changing fuel flow, speed, or temperature, and would therefore be slower or indirect in preventing surge? • Think about what feature large aircraft or industrial gas turbines use to safely operate the compressor over a range of speeds and loads.

✅ Before You Answer

• Identify which choice physically alters compressor flow angle and incidence on the rotor blades. • Separate answers that are primarily about governing fuel or temperature from those that modify compressor geometry. • Ask: which feature is commonly cited in turbine texts as a standard method to extend the surge margin of an axial compressor?