Abstract: An apparatus for optimizing blade and sealing slots of a compressor of a gas turbine comprising a rotor including a plurality of axially spaced discs and rotor blades on the discs and a stator casing surrounding the blades and forming clearance slots therewith. The blades and stator casing form a path for flow of air in a main stream in which the air is compressed and discharged at a discharge end of the compressor. A seal at the last of the discs opposes outflow of compressed air thereat and forms sealing slots through which leakage air can flow from the main stream. The leakage air is conveyed from the compressor and a portion thereof is diverted as a secondary stream in a direction opposite the main stream of air flow in the compressor, and discharged towards the last rotor disc and at least the next adjacent rotor disc to flow thereon.