US Patent 10161314 Vented buffer air supply for intershaft seals

Aspects of the disclosure are directed to a system associated with an engine having a central longitudinal axis, comprising: a first shaft axially extend along the central longitudinal axis, a second shaft coaxial with the first shaft, a first air seal that seals between the first shaft and the second shaft at a first axial location, a second air seal that seals between the first shaft and the second shaft at a second axial location, a high pressure compressor section that provides air to the first air seal and the second air seal, at least one buffer passage, and a meter connected to the buffer passage that exhausts a portion of the air.