Centrifugal Compressor Impeller Backplate Offtake for Bleed Air Recovery
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Solution Overview
Problem
Gas turbine engines face challenges in managing heat generation and windage at the compressor impeller tips, leading to reduced efficiency and component lifetime due to the use of bleed air that is discarded, sacrificing pressure and temperature.
Innovation Solution
A centrifugal compressor design with an impeller backing plate featuring bleed holes and a manifold that redirects compressed gases to the turbine, bypassing the combustor, combined with a seal system to reuse bleed air effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If bleed air is used to cool the compressor impeller, then heat generation is reduced, but pressure and temperature are sacrificed
Solution Approach 1:
The patent recovers the bleed air that would otherwise be discarded after cooling the impeller. The seal cavity captures this cooled, pressurized air and redirects it to the turbine, transforming a waste stream into a useful resource for turbine cooling or work extraction.
Solution Approach 2:
The seal cavity acts as an intermediary chamber between the compressor back cavity and the turbine. It captures the bleed air, maintains its pressure, and provides a controlled path for the air to reach the turbine, enabling the transfer of useful energy.
2Temperature
If bleed air is discarded after cooling, then cooling function is achieved, but operational efficiency decreases
Solution Approach 1:
Instead of discarding the cooled bleed air, the system recovers it through the seal cavity and directs it to the turbine. This recovery process maintains operational efficiency by utilizing the thermal and pressure energy that would otherwise be wasted.
Solution Approach 2:
The system uses its own bleed air, after it has served its cooling function, to provide additional useful work in the turbine. The air essentially serves multiple functions: cooling the impeller and then contributing to turbine operation.
3Duration of action of stationary object
If windage heat is reduced at impeller tips, then component lifetime improves, but system complexity increases
Solution Approach 1:
The seal cavity and manifold structure serve multiple functions: they capture bleed air for impeller cooling, redirect the cooled air to the turbine, and prevent harmful windage at the impeller tips. This multi-functionality reduces overall system complexity by combining several functions into a single integrated structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces windage heat generation at the impeller tips while maintaining high pressure for reuse in engine components, enhancing operational efficiency and component life.
Implementation Method 1
Gas turbine engines with one or more stages of axial and/or centrifugal compression
Implementation Method 2
The forward and aft sealing elements may engage the impeller backing plate of the centrifugal compressor to fluidly separate the back cavity of the compressor from the turbine
Implementation Method 3
the bleed holes may be arranged radially inwardly from an outlet tip of the impeller blades so as to allow for compressed gases discharged from the outlet tip of the impeller blades to move over the outlet tip and radially along a portion of the impeller disk
Data Source
AI summary
A gas turbine engine includes a fan, a compressor, a combustor, and a turbine. The compressor compresses gases entering the gas turbine engine. The combustor receives the compressed gases from the compressor and mixes fuel with the compressed gases. The turbine receives the hot, high pressure combustion products created by the combustor by igniting the fuel mixed with the compressed gases. The turbine extracts mechanical work from the hot, high pressure combustion products to drive the fan and compressor.