Bladed Disk Segmentation for Flutter Mitigation

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Solution Overview

Problem

Bladed disks in gas turbine engines and boundary layer ingestion propulsion systems are susceptible to flutter and forced response, which can cause damage, and existing methods to mitigate this often require complex blade design modifications that affect airflow and fan performance.

Innovation Solution

A bladed disk design featuring a rotor disk with partial breaks or divides arranged circumferentially around the axis of rotation, introducing asymmetric stiffness and isolating blade foundations to prevent vibration transfer, while maintaining the disk as a single unitary piece, and optionally incorporating filler material for additional damping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex blade design modifications are made to reduce flutter, then flutter resistance is improved, but fan performance and airflow are worsened

Engineering Contradiction:

Improveflutter resistanceVSAvoidfan performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The rotor disk is segmented into different regions using divides that extend radially inward from the outer surface, creating isolated foundation portions for each blade while maintaining overall structural integrity. This segmentation allows independent vibration control for each blade without affecting other blades, reducing flutter while preserving fan performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The divides are positioned at specific radial locations to create local variations in stiffness and vibration isolation. By concentrating the vibration isolation function at the blade foundation regions rather than modifying the entire blade structure, the solution reduces flutter locally without impacting the aerodynamic performance of the blade airfoils.

Inventive Principle:

Principle #3Local quality

2Reliability

If vibration isolation between blades is implemented, then flutter is reduced, but structural complexity increases

Engineering Contradiction:

Improvevibration isolationVSAvoiddisk structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The divides may be formed using different materials or material properties than the surrounding rotor disk material, allowing tailored vibration isolation characteristics. This enables effective flutter reduction through material differentiation rather than complex geometric features.

Inventive Principle:

Principle #40Composite materials

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 design reduces flutter and maintains fan performance by allowing identical blade design without airflow modifications, while providing structural continuity and improved strength through meta matrix composite materials.

Implementation Method 1

The variation between the divides introduces asymmetric stiffness into the material supporting the blades and hence detunes the blades

Methodology Applied

Scientific EffectAsymmetric stiffness:

Implementation Method 2

the divides isolate material supporting each blade, so vibration cannot be passed around the circumference of the central rotor disk

Methodology Applied

Scientific EffectVibration isolation: Damping

Implementation Method 3

providing structural continuity and improved strength through meta matrix composite materials

Methodology Applied

Scientific EffectComposite materials: Composite Materials

Data Source

PatentUS10641112B2Bladed disk

Publication Date: 2020.05.05 ROLLS ROYCE PLC

AI summary

A bladed disk may be arranged to rotate about an axis of rotation and including a rotor disk having an axial length extending from a first end to a second end, along the axis of rotation and a radial thickness extending between a first radius from the axis of rotation and a second radius from the axis of rotation, less than the first radius. The bladed disk may include a plurality of blades formed integrally with the rotor disk and arranged circumferentially around the rotor disk, and a first set of divides and a second set of divides, each divide comprising a partial break in the rotor disk extending axially from the first end of the rotor disk to the second end of the rotor disk and radially from the first radius to a third radius, less than the first radius and greater than the second radius.