Open-Rotor Fan Blade Break Lines for Blade-Out Damage Mitigation
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Solution Overview
Problem
The challenge of mitigating fan blade out damage in aircraft engines, which can cause catastrophic damage to the fuselage due to the impact of a broken blade fragment, is not adequately addressed by existing technologies.
Innovation Solution
Designing fan blades with strategically placed break lines that divide the blade into sections with parametrically defined masses, ensuring that when subjected to excessive stress, the blade breaks into smaller, less damaging fragments by controlling momentum and kinetic energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fan blade is designed to break into smaller sections when subjected to excessive stress, then the damage to the fuselage is reduced, but the blade structure becomes more complex with break lines
Solution Approach 1:
The blade is divided into multiple sections by forming break lines within the blade body. These break lines create predetermined locations where the blade will fracture into smaller, lighter sections when subjected to excessive stress, thereby reducing the mass and damage potential of any single fragment that impacts the fuselage.
Solution Approach 2:
The break lines are formed with specific local properties - having less rigidity than surrounding portions of the blade body. This localized reduction in rigidity at the break line locations ensures that fractures occur at these predetermined positions rather than randomly throughout the blade, allowing controlled segmentation while maintaining overall blade integrity during normal operation.
2Object-affected harmful factors
If the blade is made lighter by creating break lines and sections, then the kinetic energy of fragments is reduced, but the blade strength is compromised
Solution Approach 1:
The break lines are pre-formed within the blade body during manufacturing, creating predetermined fracture locations before the blade enters service. These break lines are positioned and designed so that under excessive stress conditions, the blade will fracture at these predetermined locations into sections with parametrically defined masses that limit kinetic energy, rather than fracturing randomly into potentially more dangerous fragments.
Solution Approach 2:
The blade structure is modified by changing the rigidity parameter at specific locations where break lines are formed. The break lines have less rigidity than surrounding portions of the blade body, creating a controlled weakness that allows the blade to fracture into lighter sections with reduced mass and kinetic energy when subjected to excessive stress, while maintaining adequate strength during normal operation.
3Quantity of substance
If break lines are formed to control fracture locations, then fragment mass is reduced, but manufacturing complexity increases
Solution Approach 1:
The blade manufacturing process incorporates the formation of break lines that segment the blade body into predetermined sections. These break lines are formed as integral features during blade fabrication, creating controlled locations where the blade will fracture into smaller mass sections when subjected to excessive stress, thereby reducing fragment mass without requiring post-manufacturing assembly of separate components.
Solution Approach 2:
The manufacturing process is enhanced by forming break lines with modified rigidity parameters within the blade body. These break lines are created during blade fabrication using appropriate manufacturing techniques, establishing predetermined fracture locations that control fragment mass while being integrated into the overall blade manufacturing workflow rather than requiring separate addition steps.
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
The solution minimizes the risk of large, high-energy fragments by ensuring that the blade breaks into sections with balanced kinetic energy and momentum, reducing the potential damage to the aircraft fuselage during a blade out event.
Implementation Method 1
a break line formed within the blade body at a location that divides the blade body into sections having parametrically defined masses. The break line has less rigidity than surrounding portions of the blade body that surround the break line. The blade body is configured to break into the sections when subjected to an excessive stress.
Data Source
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AI summary
An open rotor gas turbine engine (102) includes a gearbox (104) and a fan blade system (100) coupled to the gearbox (104). The fan blade system (100) includes a hub (120) and a plurality of fan blades (110) affixed to the hub (120). At least one of the fan blades (110) includes a blade body and a break line (L1) formed within the blade body at a location that divides the blade body into sections (131, 132) having parametrically defined masses. The break line (L1) has less rigidity than surrounding portions of the blade body that surround the break line (L1). The blade body of at least one fan blade (110) is configured to break into the sections when subjected to an excessive stress.