Gas Turbines - Compressors: DGCA Technical General questions

The compressor raises air pressure before combustion and sets much of the engine's efficiency. The centrifugal type flings air outwards through an impeller and diffuser; the axial type passes it through rows of rotor and stator blades. Compressor items come up often.

Across the 79 questions the themes are stage layout, blade twist, stall and surge, bleed valves, guide vanes and centrifugal against axial. Exam sessions account for 6 of them.

A stall is a flow breakdown over some blades; a surge is a breakdown through the whole compressor, often with reversed flow. Bleed valves open at low rpm and close as rpm rises. The annulus narrows towards the rear to keep axial velocity steady as the air grows denser.