In order to cool rotor disks and internal vane structure of a gas turbine engine, cooling air circulated through stator vanes is directed to inter-stage cavities between adjacent rotor disks. However, due to the rotation of the rotor disks during operation of the gas turbine engine, windage occurs in the cavities around the stator vane structure. Windage increases the temperature of the cooling air, which reduces the efficiency of the cooling air flow. Further, as platform seals wear, hot working gas is ingested into the inter-stage cavities where sensitive turbine components may become damaged from exposure to the high temperatures of the hot working gas.