Rotating Shaft Active Damping for Torsional Resonance Control

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Solution Overview

Problem

Gas turbine engines face challenges in controlling unforeseen interactions that can lead to torsional resonance, potentially causing shaft failure due to significant resonance amplitudes, especially in lightly damped low and intermediate pressure spools.

Innovation Solution

A method and system for actively controlling torsional resonance by measuring the rotational velocity of the shaft, extracting the oscillatory term, and applying a torque component modulated at the same frequency as the resonance to counteract it, using fuel flow modulation or an electric motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If active damping control is implemented to reduce torsional resonance, then shaft reliability is improved, but device complexity increases

Engineering Contradiction:

Improveshaft reliabilityVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements active damping control by measuring shaft rotational velocity, extracting the oscillatory term representing torsional resonance, and applying a counteracting torque component modulated at the resonance frequency. This feedback loop continuously monitors and actively suppresses torsional resonance, improving shaft reliability by preventing resonance-induced shaft failure despite the added control system complexity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces passive mechanical damping designs with an active control system that uses measurement and computation. Instead of relying on mechanical damping structures, the system uses sensors to detect resonance and electronically generates counteracting torque signals, substituting mechanical solutions with a control-based approach that achieves the same reliability goal

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If avoid-by-design rules are used to prevent resonance, then device complexity is reduced, but adaptability worsens due to unforeseen interactions

Engineering Contradiction:

Improvecontrol system complexityVSAvoidsystem adaptability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent transitions from static avoid-by-design rules to a dynamic active control system that adapts to actual operating conditions. The system continuously measures shaft rotational velocity and adjusts the counteracting torque in real-time based on the detected oscillatory term, enabling the system to adapt to unforeseen interactions and changing operating conditions rather than relying on predetermined design constraints

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If measurement frequency is increased to accurately capture torsional resonance, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improverotational velocity measurement precisionVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by measuring at a frequency higher than the minimum required (at least twice the torsional resonance frequency) to ensure accurate capture of the oscillatory term, while avoiding excessive measurement frequencies that would unnecessarily increase energy consumption. This balanced approach achieves sufficient measurement precision for resonance detection without excessive energy use

Inventive Principle:

Principle #16Partial or excessive 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 approach reduces or eliminates torsional resonances, thereby extending shaft life and reducing the need to design-out resonance-inducing interactions, making the system more adaptable and efficient.

Implementation Method 1

measuring the rotational velocity of the shaft

Methodology Applied

Scientific EffectRotational velocity measurement:

Implementation Method 2

active damping of a shaft can be used to address resonances caused by such unforeseen interactions

Methodology Applied

Scientific EffectActive damping: Damping

Implementation Method 3

applying a torque component to the shaft, the torque component being modulated at the same frequency as the torsional resonance to counteract the torsional resonance

Methodology Applied

Scientific EffectTorque modulation:

Data Source

PatentUS11300059B2Shaft resonance control

Publication Date: 2022.04.12 ROLLS ROYCE PLC

AI summary

A method of actively controlling torsional resonance of a rotating shaft of an engine is provided. The shaft has a rotational velocity characterised by a low frequency, rotational velocity term and a high frequency, oscillatory term superimposed on the low frequency term, the oscillatory term being caused by torsional resonance. The method including: measuring the rotational velocity of the shaft; extracting the oscillatory term from the measured rotational velocity; and on the basis of the extracted oscillatory term, applying a torque component to the shaft, the torque component being modulated at the same frequency as the torsional resonance to counteract the torsional resonance.