External Shaped Charge for Fan Blisk Airfoil Release

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Solution Overview

Problem

Conventional methods for testing turbofan engines during fan blade off events are inadequate, particularly for blisk designs, as they fail to precisely and safely simulate the release of fan blades, which is critical for safety certifications and aerodynamic testing.

Innovation Solution

An external shaped charge arrangement is applied to the fan blade, with detonators and a charge holder to selectively weaken and release the airfoil, simulating a blisk fan blade off event by cutting the airfoil radially outside the blade platform, allowing for controlled and precise release of the fan blade.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional drilling methods are used to release fan blades, then the release can be achieved, but the precision and control of the release timing are insufficient

Engineering Contradiction:

Improverelease timing precisionVSAvoidcharge arrangement complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The fan blade is divided into distinct functional zones: the airfoil section that is released, the blade platform that remains attached, and the root section. The shaped charge is positioned to segment only the airfoil portion, allowing precise control over which part is released while maintaining other critical sections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The airfoil is selectively weakened only in the specific region where the shaped charge will detonate, while other parts of the blade maintain their full strength. This localized modification allows the blade to be released at a precise location and time without compromising the structural integrity of the platform and root.

Inventive Principle:

Principle #3Local quality

2Reliability

If the entire fan blade is released, then the containment case can be tested, but the mass of the projectile increases reducing safety

Engineering Contradiction:

Improvecontainment case validationVSAvoidprojectile mass

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

Only the necessary portion of the fan blade (the airfoil) is extracted and released for testing purposes. The blade platform and root remain attached to the rotor disk, eliminating unnecessary mass from the projectile while still providing sufficient data to validate containment case performance.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of releasing the entire blade (excessive action), only the minimal necessary portion (the airfoil) is released. This partial release provides adequate testing data while significantly reducing the projectile mass and associated safety risks.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If the airfoil is not selectively weakened, then the blade structure remains intact, but the shaped charge cannot achieve precise release

Engineering Contradiction:

Improverelease location precisionVSAvoidairfoil strength

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The airfoil is preliminarily weakened through material extrication before the actual release event. This pre-modification creates a controlled weakness that ensures the shaped charge will release the airfoil at the precise desired location without causing unintended damage to other blade sections.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The airfoil strength is modified locally only where needed for release, while the rest of the blade maintains its full structural strength. This localized weakening allows precise release control without compromising the overall blade integrity before release.

Inventive Principle:

Principle #3Local quality

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 method enables precise and controlled release of the fan blade, reducing the mass of the projectile and improving safety and aerodynamic testing, meeting certification requirements by simulating the failure point of a blisk design without releasing the blade root or platform, thus validating containment case performance.

Implementation Method 1

An external shaped charge arrangement is applied to the fan blade, with detonators and a charge holder to selectively weaken and release the airfoil

Methodology Applied

Scientific EffectShaped charge: Shaped Charge

Implementation Method 2

detonating the external shaped charge such that the airfoil is released at a selected time

Methodology Applied

Scientific EffectDetonation: Detonation

Data Source

PatentUS10260512B2Method for release of fan blisk airfoil with external shaped charge

Publication Date: 2019.04.16 ROLLS ROYCE CORP

AI summary

According to one aspect, a method of releasing a fan blade for testing a turbofan engine includes arranging an external shaped charge about an airfoil and modifying the airfoil by extricating one or more portions of material from one or more sides of the airfoil. The method further includes detonating the external shaped charge such that the airfoil is released at a selected time.