High Compressor Clearance Reduction via Bowed Rotor Management

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Solution Overview

Problem

Gas turbine engines face challenges with bowed rotor conditions due to thermal expansion, leading to potential damage from rotor blade contact with engine surfaces, which existing methods address by increasing compressor build clearances, resulting in reduced efficiency and increased fuel burn.

Innovation Solution

Implementing a system with multiple bowed rotor management systems, including rotor abrasion, core-turning motor, dry motoring, and damper systems, to maintain minimal clearances and prevent damage by mitigating bowed rotor conditions through controlled rotation and vibration management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If compressor build clearances are opened to prevent rotor blade contact during bowed rotor condition, then engine reliability is improved, but compressor efficiency is reduced and fuel burn increases

Engineering Contradiction:

Improveengine reliabilityVSAvoidfuel burn

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system performs preliminary actions by rotating the compressor rotor before engine start using a core-turning motor or dry motoring system. This preliminary rotation equalizes thermal distribution and prevents bowed rotor conditions, allowing the engine to start with tighter clearances without risking blade contact damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts rotor position and rotation speed during the pre-start phase. By controlling the rotor to rotate at specific speeds and directions, the system actively manages thermal expansion patterns and prevents bowing, enabling safe operation with reduced build clearances.

Inventive Principle:

Principle #15Dynamics

2Reliability

If compressor build clearances are opened to prevent rotor blade contact during bowed rotor condition, then engine reliability is improved, but compressor stability is reduced

Engineering Contradiction:

Improveengine reliabilityVSAvoidcompressor stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses sensors to monitor rotor position, temperature distribution, and vibration patterns in real-time. This feedback enables the control system to adjust rotation speed and direction dynamically, maintaining optimal thermal balance and preventing bowed rotor conditions that would compromise compressor stability.

Inventive Principle:

Principle #23Feedback

3Reliability

If multiple bowed rotor management systems are implemented to prevent damage, then rotor blade protection is improved, but device complexity increases

Engineering Contradiction:

Improverotor blade protectionVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system merges multiple protection functions into an integrated control architecture. The core-turning motor, dry motoring system, and sensor monitoring are coordinated through a single control system that manages all bowed rotor prevention functions, reducing operational complexity while maintaining comprehensive protection.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The control system performs multiple functions: it monitors thermal conditions, controls rotor rotation speed and direction, coordinates pre-start rotation sequences, and manages engine startup. This multi-functional approach consolidates what would otherwise be separate systems into a unified solution.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 approach enables tighter compressor build clearances, enhancing stability and reducing fuel burn by effectively managing bowed rotor conditions without compromising engine safety.

Implementation Method 1

a damper system to maintain minimal clearances and prevent damage by mitigating bowed rotor conditions

Methodology Applied

Scientific EffectVibration damping: Damping

Implementation Method 2

When this occurs thermal expansion may cause deflection of components of the engine which may result in a 'bowed rotor' condition

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3318727B1High pressure compressor build clearance reduction

Publication Date: 2020.07.01 RTX CORP

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AI summary

An aspect includes a system including a high compressor (52) of a gas turbine engine (10) having a ratio of a cold-rotor build clearance (CLR) to a span (S) between 0.7% and 7%. The cold-rotor build clearance (CLR) is defined for a plurality of rotor blades (60) of the high compressor (52) with respect to an engine casing assembly interior surface (64) of the high compressor (52), and the span (S) is defined as a gap between a rotor disk (65) of the high compressor and the engine casing assembly interior surface (64) of the high compressor (52) for at least a last two stages (57) of the high compressor (52) closest to a combustor section of the gas turbine engine. The system also includes at least two bowed rotor management systems for the gas turbine engine (10) to prevent damage to the rotor blades (60) for a bowed rotor condition of the high compressor (52) under a plurality of operating conditions.