US Patent 11346367 Compressor rotor casing with swept grooves

The compressor for a gas turbine engine includes a rotor with blades, and a shroud surrounding the rotor and having an inner surface surrounding tips of the blade. A plurality of grooves are defined in the inner surface of the shroud adjacent the blade tips, the grooves extending circumferentially about the shroud and extending radially from groove inlet openings defined in the inner surface to closed end surfaces of the grooves. The grooves are axially spaced-apart from each other and disposed axially between the leading and trailing edges of the blades. The grooves have a forwardly swept angle from the inner surface, and circumferential interruptions such that the grooves extend non-continuously around the shroud circumference.