Compressor cooling system for a turbofan engine

A turbofan engine for an aircraft, comprising:

• a compressor section including a compressor casing and a centrifugal compressor, an annular main gas path extending axially through a core casing of the turbofan engine within the compressor section, the centrifugal compressor including an impeller that rotates within a shroud surrounding blades of the impeller, the shroud being secured to the compressor casing, a tip clearance defined between blades of the impeller and the shroud;
• a bypass duct disposed radially outward of the core casing and defining a bypass gas path extending therethrough;
• a cooling conduit extending between an inlet in the bypass duct and an outlet adjacent to the compressor casing, a protrusion disposed about an opening to the inlet and protruding radially outwardly into the bypass duct, the cooling conduit including a manifold and a perforated screen adjacent the outlet;
• and
• a valve in selective fluid communication with the inlet of the cooling conduit, the valve fluidly coupled to a source of high pressure air and being controlled to move between a closed position and an open position, wherein in the open position during operation of the turbofan engine a flow of the high pressure air is injected adjacent the inlet of the cooling conduit in a direction tangential to the bypass gas path, and in the closed position during operation of the turbofan engine the high pressure air is substantially prevented from being injected into the cooling conduit or the bypass duct.