Turbine engine with centrifugal compressor having impeller backplate offtake

A gas turbine engine comprising

• a centrifugal compressor including an impeller mounted for rotation about an axis and an impeller backing plate,
• the impeller including an impeller disk and impeller blades that extend from a forward side of the impeller disk,
• the 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, and
• 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 flow along a portion of the aft side of the impeller disk before flowing through the number of bleed holes,
• a diffuser configured to receive a second portion of the compressed gases from the outlet tips of the impeller blades as compressor discharge air, and discharge the compressor discharge air to a plenum surrounding a combustor,
• a turbine including a rotor for rotation about the axis and a seal coupled with the rotor for rotation therewith, the seal including a forward sealing element and an aft sealing element that each engage the impeller backing plate of the centrifugal compressor to fluidly separate the back cavity of the centrifugal compressor from directly communicating with a wheel cavity of the turbine,
• wherein a seal cavity is formed between the forward sealing element and the aft sealing element,
• wherein the wheel cavity of the turbine is fluidly separated from the seal cavity by the aft sealing element, 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 the compressed gases moving through the number of bleed holes and conduct the first portion of the compressed gases from the centrifugal compressor to the wheel cavity of the turbine,
• wherein the impeller backing plate is formed to include a plurality of holes that extend through the impeller backing plate, the plurality of holes opening onto the plenum and opening into the seal cavity to transmit a portion of the compressor discharge air from the diffuser to the seal cavity.

A gas turbine engine comprising

• a centrifugal compressor including an impeller mounted for rotation about an axis and an impeller backing plate,
• the impeller including an impeller disk and impeller blades that extend from a forward side of the impeller disk,
• the 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, and 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 tip of the impeller blades to flow along a portion of the aft side of the impeller disk before flowing through the number of bleed holes,
• a second portion of the compressed gases being discharged from the centrifugal compressor as a compressor discharge air into a plenum surrounding a combustor,
• a turbine including a rotor for rotation about the axis and a seal coupled with the rotor for rotation therewith,
• the seal including a forward sealing element and an aft sealing element that each engage the impeller backing plate of the centrifugal compressor to fluidly separate the back cavity of the centrifugal compressor from directly communicating with a wheel cavity of the turbine,
• wherein a seal cavity is formed between the forward sealing element and the aft sealing element,
• wherein the wheel cavity of the turbine is fluidly separated from the seal cavity by the aft sealing element, 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 the compressed gases moving through the number of bleed holes and conduct the first portion of the compressed gases from the centrifugal compressor to the wheel cavity of the turbine,
• wherein the impeller backing plate is formed to include a plurality of holes that extend through the impeller backing plate, the plurality of holes opening onto the plenum and opening into the seal cavity to transmit a first portion of the compressor discharge air from the centrifugal compressor to the seal cavity, and
• wherein the plurality of holes formed in the impeller backing plate are circumferentially offset from the number of circumferentially spaced apart channels formed by the manifold.