Centrifugal Compressor Impeller Axial Load and Cooling Control
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Solution Overview
Problem
Gas turbine engines face challenges in managing axial thrust bearing load, turbine cooling, and bleed flow efficiently, particularly in controlling net axial forces on impellers and directing air for effective turbine component cooling across varying operating conditions.
Innovation Solution
The design incorporates a centrifugal compressor with an impeller and combustor configuration that includes an inner combustor case with cooling holes, passageways, and bleed holes to direct compressor discharge air into the turbine wheel cavity and air plenum, allowing for controlled axial force application and turbine cooling, using a manifold and sealing elements to manage air flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air is directed from the centrifugal compressor to the turbine for cooling turbine components, then turbine life and performance are improved, but the complexity of the air flow management system increases
Solution Approach 1:
The air flow management system is segmented into multiple independent pathways: a first pathway directs air through cooling holes in the inner combustor case to the wheel cavity for turbine cooling, while a second pathway directs air through passageways to the air plenum for rotor assembly cooling. This segmentation allows each pathway to be optimized independently, managing complexity through modular design.
Solution Approach 2:
The inner combustor case serves as an intermediary structure that facilitates air distribution. It incorporates cooling holes and passageways that act as intermediaries to direct compressed air to different cooling zones, simplifying the overall system architecture by using existing structural components as flow distribution elements.
2Stability of the object's composition
If the net axial force on the impeller is controlled to remain in a single axial direction across all operating conditions, then the stability of operation is improved, but the complexity of load control mechanisms increases
Solution Approach 1:
The air flow management system performs multiple functions simultaneously: it cools turbine components, controls impeller axial loading, and manages bleed flow. By using the same air distribution infrastructure (inner combustor case with cooling holes and passageways) to achieve both cooling and load control, the system avoids additional dedicated mechanisms, reducing overall complexity.
Solution Approach 2:
The system controls impeller axial loading by varying the pressure and flow parameters of compressed air delivered to the impeller back cavity. By adjusting these parameters across different operating conditions, the net axial force is maintained in a single direction without requiring mechanical load control mechanisms.
3Temperature
If compressor discharge air is bled radially inward from impeller blade outlet tips for cooling, then turbine component cooling is enhanced, but the loss of compressed air increases
Solution Approach 1:
Bleed holes are positioned at specific radial locations inward from the impeller blade outlet tips, creating localized cooling zones where compressed air is bled. This local quality approach ensures cooling is applied precisely where thermal loads are highest on turbine components, maximizing cooling efficiency while minimizing the total amount of air bled from the compressor discharge.
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
This configuration ensures consistent net axial force on the impeller, enhances turbine component cooling, and optimizes bleed flow management, improving engine performance and longevity by applying compressed air efficiently across different operating conditions.
Implementation Method 1
The inner combustor case may be formed to include a cooling hole that extends through the inner combustor case and opens directly into the wheel cavity to direct a first portion of the compressor discharge air through the wheel cavity and into the gas path of the turbine
Implementation Method 2
The inner combustor case may be formed to define a passageway that extends through the inner combustor case and opens into the air plenum to direct a second portion of the compressor discharge air from the combustor directly into the air plenum
Implementation Method 3
Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine
Data Source
AI summary
A gas turbine engine includes 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 compressor and a fan, shaft, or propeller.