US Patent 9115594 Compressor casing treatment for gas turbine engine

An axial flow compressor for a gas turbine engine is disclosed having a casing treatment that includes a shrouded rotor and an airflow member disposed in a passage between a casing and the shrouded rotor. In one form the airflow member is stationary with the casing and in another the airflow member is coupled to rotate with the shrouded rotor. The airflow member can have an airfoil shape in some embodiments. A passage inlet that extracts working fluid and provides it to the passage can be formed between a leading edge of the rotor and a trailing edge. A passage outlet can be formed upstream of the leading edge of the rotor.