Clutched Compressor Rotor Stage for Gas Turbine Temperature Relief

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Solution Overview

Problem

The increasing compressor pressure ratios and internal temperatures in gas turbine engines pose a challenge for material capabilities, particularly in the high-pressure compressor section, where large or complex air coolers are needed to mitigate temperatures, otherwise leading to flight restrictions.

Innovation Solution

A clutched compressor section with a decouable rotor stage that can switch between coupled and decoupled conditions, utilizing a clutch mechanism with engagement members in an interference fit or controlled by an electromagnetic field, allowing the decouable stage to freely rotate independently and reduce fluid compression and temperature when rotational speed exceeds a threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If compressor pressure ratio and operating envelope are increased, then engine performance and productivity are improved, but compressor temperature and thermal stress increase beyond material capabilities

Engineering Contradiction:
Improveengine performanceVSAvoidcompressor temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The compressor section employs a dynamic clutch mechanism that allows the compressor to switch between coupled and decoupled states. In the coupled state, all compressor stages operate together for maximum performance. When temperature thresholds are exceeded, the clutch disengages, allowing the rear compressor stages to rotate independently or be driven at different speeds, dynamically adjusting the compression ratio to reduce thermal stress while maintaining acceptable performance levels.

Inventive Principle:
Principle #15Dynamics

2Temperature

If large or complex air coolers are added to mitigate temperatures, then temperature control is improved, but device complexity and weight increase

Engineering Contradiction:
Improvecompressor temperature controlVSAvoidcooler system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

Instead of adding static cooling equipment, the invention uses a dynamic control approach where the clutch mechanism modulates the operation of compressor stages. By selectively decoupling rear stages when temperature limits are approached, the system dynamically manages thermal loads without requiring additional coolers, thereby avoiding increased complexity and weight.

Inventive Principle:
Principle #15Dynamics

3Reliability

If flight restrictions are imposed to manage temperature, then material durability is preserved, but operational versatility and productivity are reduced

Engineering Contradiction:
Improvematerial durabilityVSAvoidflight operation flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The clutch mechanism provides real-time dynamic adjustment of compressor operation based on temperature conditions. During normal operation, the full compressor envelope is available for high performance. When temperature thresholds are exceeded, the clutch automatically decouples rear stages to reduce thermal stress, protecting materials without requiring pre-imposed flight restrictions. This maintains both durability and operational flexibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The compressor system monitors its own temperature conditions and automatically adjusts its operation through the clutch mechanism. When thermal limits are approached, the system self-regulates by decoupling rear stages, eliminating the need for external flight restrictions while protecting material durability. This autonomous control preserves full operational versatility.

Inventive Principle:
Principle #25Self-service

4Reliability

If clutch mechanism with interference fit is used to couple stages, then mechanical strength and reliability are improved, but centrifugal force at high speed causes decoupling

Engineering Contradiction:
Improvestage coupling reliabilityVSAvoidrotational speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The interference fit clutch mechanism is designed to maintain coupling at normal operating speeds through strong mechanical engagement. However, at elevated speeds beyond a threshold, centrifugal forces naturally overcome the interference fit, causing automatic decoupling. This dynamic behavior provides a passive safety mechanism that protects the compressor from excessive thermal stress at high speeds without requiring complex active control systems.

Inventive Principle:
Principle #15Dynamics

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 reduces compressor temperature and extends the operating envelope by allowing selective decoupling of rotor stages, enhancing durability and reducing thermal stress on materials, thereby avoiding the need for restrictive flight conditions.

Implementation Method 1

The first engagement member and the second engagement member are disposed in an interference fit condition in the coupled condition

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

The first engagement member and the second engagement member are disposed in an interference fit condition in the coupled condition

Methodology Applied
Scientific EffectNormal force: Force

Implementation Method 3

a threshold centrifugal force overcomes the interference fit condition to dispose the first engagement member and the second engagement member in the decoupled condition

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 4

the relative position of the first engagement member and the second engagement member is controlled with an electromagnetic field applied proximate the clutch mechanism

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentEP3431770B1Clutched compressor section for gas turbine engine
Publication Date: 2024.09.04 RTX CORP
  • EP3431770B1 patent drawingFigure 1
  • EP3431770B1 patent drawingFigure 2

AI summary

A clutched compressor section (24) of a gas turbine engine (20) coupled to a rotor shaft. The clutched compressor section includes at least one decoupleable rotor stage (64), the decoupleable rotor stage switchable between a coupled condition and a decoupled condition with a clutch mechanism (80), the coupled condition coupling the decoupleable rotor stage with the rotor shaft, the decoupled condition decoupling the decoupleable rotor stage from the rotor shaft.