Turbine engine with centrifugal compressor having impeller backplate offtake

A turbine engine comprising:

• a centrifugal compressor including
• (i) an impeller mounted for rotation about an axis and having an impeller disk and impeller blades that extend from a forward side of the impeller disk and
• (ii) an impeller backing plate arranged along an aft side of the impeller disk to define a back cavity of the centrifugal compressor between the aft side of the impeller disk and the impeller backing plate,
• the impeller backing plate formed to include a number of bleed holes arranged radially inwardly from an outlet tip of each of the impeller blades to allow a first portion of compressed gases discharged from the outlet tips of the impeller blades to move radially inward along a portion of the aft side of the impeller disk before moving through the number of bleed holes in the impeller backing plate, and
• wherein a second portion of compressed gases is discharged from the centrifugal compressor as a compressor discharge air into a plenum surrounding a combustor,
• the combustor fluidly coupled to receive a first portion of the compressor discharge air,
• a turbine fluidly coupled to the combustor and including a rotor having a shaft mounted for rotation about the axis,
• a set of turbine blades coupled to the shaft for rotation therewith, and
• a seal formed from a first sealing element and a second sealing element, wherein a seal cavity is formed between the first sealing element and the second sealing element of the seal, and
• a manifold mounted to the impeller backing plate and shaped to define a number of circumferentially spaced apart channels that receive the first portion of compressed gases moving through the number of bleed holes and carry the first portion of compressed gases from the centrifugal compressor to a wheel cavity of the turbine such that the first portion of compressed gases bypasses the combustor,
• wherein the impeller backing plate is formed to include a plurality of impingement holes that extend through the impeller backing plate,
• the plurality of impingement holes opening into the plenum surrounding the combustor and opening into the seal cavity to transmit a second portion of the compressor discharge air from the plenum to the seal cavity,
• wherein the first sealing element of the seal is configured to leak at least some of the second portion of the compressor discharge air to the back cavity as a first leaked air so that the first leaked air the back cavity.