Gas turbine engine impeller system for an intermediate pressure (IP) compressor

A gas turbine engine comprising:

• a shaft;
• a turbine assembly rotationally coupled to the shaft, the turbine assembly driven by hot gases discharged from a combustion chamber;
• a compressor assembly rotationally coupled to the shaft, the compressor assembly having a centrifugal impeller for pressurizing and impelling air into the combustion chamber;
• a mounting structure coupled to a case of the gas turbine engine;
• a thrust bearing attached to the mounting structure and attached to the shaft such that the shaft is rotatable relative to the mounting structure;
• an impeller shroud covering a bladed portion of the centrifugal impeller, the impeller shroud having a first flange extending therefrom along a first extension;
• a radial diffuser having a second flange extending therefrom along a second extension, the first extension in contact with the second extension, the radial diffuser positioned to receive compressed air from the compressor assembly, the radial diffuser having the second flange and having a first strut attached to the mounting structure, wherein the first flange of the impeller shroud is directly attached to the second flange via the first and second extensions;
• a transition duct positioned to receive compressed air from the radial diffuser, the transition duct having a second strut attached to the mounting structure;
• and
• a piston ring seal coupled between the transition duct and the radial diffuser, the piston ring seal configured to prevent air from passing through the seal while allowing relative motion between the transition duct and the radial diffuser.

A method of assembling a centrifugal compressor for a gas turbine engine comprising:

• attaching a centrifugal impeller of a compressor to a rotational shaft;
• covering a bladed portion of the centrifugal impeller with a shroud;
• attaching a diffuser to the shroud via a pair of flanges, wherein one of the pair of flanges extends from the diffuser in a first direction and the other of the pair of flanges extends from the shroud in the first direction, and the pair of flanges are in direct contact with one another;
• attaching the diffuser to an intercase via a strut that is mounted as an aft-extending leg to a base of the intercase;
• and
• coupling the diffuser to a transition duct via a sealing assembly, wherein the sealing assembly is configured to prevent air from passing through the sealing assembly while allowing relative motion to occur between the transition duct and the diffuser.