Embedded Electrical Machine Cooling in Gas Turbines

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Solution Overview

Problem

Gas turbine engines face challenges in effectively cooling electrical machines embedded within the engine, particularly those located at least partially inward of the core airflow path, where high temperatures from exhaust gases pose a risk to the electrical machine's operation and longevity.

Innovation Solution

A cooling system is implemented that directs liquid coolant radially inward past the outer electrical machine stator and onto the inner electrical machine rotor using a coolant passageway, ensuring effective heat removal from both the rotor and its support, while maintaining separate coolant circuits for the stator and rotor compartments to prevent mixing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the electrical machine is located inward of the core airflow path to save space and improve integration, then the device complexity is reduced, but the temperature increases due to proximity to hot exhaust gases

Engineering Contradiction:

Improveengine integration complexityVSAvoidelectrical machine temperature

Core Design Contradiction:

Device complexityVSTemperature

Solution Approach 1:

The cooling system is segmented into separate circuits: a first coolant circuit cools the stator through dedicated passages, while a second coolant circuit cools the rotor through separate passages. This segmentation allows independent optimization of cooling for each component, effectively managing temperatures in the compact inward location

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A thermal barrier or insulation layer is introduced between the electrical machine components and the hot exhaust gases. This intermediary protects the electrical machine from direct thermal exposure while maintaining the space-efficient inward placement

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If a cooling system is added to remove heat from the electrical machine, then the temperature is controlled, but the device complexity increases

Engineering Contradiction:

Improveelectrical machine temperatureVSAvoidcooling system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The cooling passages for both stator and rotor are integrated into the electrical machine assembly during manufacturing. The coolant circuits are merged with the existing structural components, eliminating the need for separate external cooling apparatus and reducing overall system complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electrical machine components (stator and rotor) incorporate internal coolant passages that allow them to cool themselves during operation. The coolant flows directly through the components, enabling self-cooling without requiring complex external cooling mechanisms

Inventive Principle:

Principle #25Self-service

3Reliability

If separate coolant circuits are used for stator and rotor, then the cooling effectiveness is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvecooling system reliabilityVSAvoidcoolant passage alignment precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The coolant passages are pre-formed and precisely positioned during the manufacturing of the stator and rotor components. By establishing the correct geometry and alignment during fabrication rather than requiring post-assembly adjustment, the precision requirements are managed through controlled manufacturing processes

Inventive Principle:

Principle #10Preliminary action

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 solution effectively manages the high temperatures within gas turbine engines by efficiently cooling the electrical machines, enhancing their operational reliability and extending their lifespan by maintaining them within a desired temperature range.

Implementation Method 1

directing a liquid coolant radially inward past the outer electrical machine stator and toward an inner electrical machine rotor using a coolant passageway. The liquid coolant is directed onto and/or through one or both of the inner electrical machine rotor and a rotor support thereby removing heat from the inner electrical machine rotor

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

The liquid coolant is directed onto and/or through one or both of the inner electrical machine rotor and a rotor support thereby removing heat from the inner electrical machine rotor

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11719122B2Gas turbine engines including embedded electrical machines and associated cooling systems

Publication Date: 2023.08.08 GENERAL ELECTRIC CO POLSKA SP ZOO

AI summary

A method of removing heat from an electrical machine located in a gas turbine engine at least partially inward of a core airflow path in a radial direction, the electrical machine comprising an outer electrical machine stator and an inner electrical machine rotor is provided. The method includes directing a liquid coolant radially inward past the outer electrical machine stator and toward an inner electrical machine rotor using a coolant passageway. The liquid coolant is directed onto and/or through one or both of the inner electrical machine rotor and a rotor support thereby removing heat from the inner electrical machine rotor.