Composite Gas Turbine Blade Voids for Bird Strike Whiplash Control
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Solution Overview
Problem
Composite materials used in gas turbine blades are brittle and prone to disintegration due to whiplash motion caused by bird strikes, which is destructive and leads to potential engine damage, and traditional reinforcement methods like thickening the trailing edge or adding metal capping compromise aerodynamic efficiency and weight balance.
Innovation Solution
The use of deformation pulse wave reflection trips and delamination techniques, including projections and reflectors to create standing waves and dissipate energy, combined with delamination initiation points and self-healing fluids to manage deformation and prevent damage propagation to the trailing edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used to form blades, then weight is reduced, but the blade becomes more brittle and prone to disintegration under bird strike
Solution Approach 1:
The patent introduces pre-configured voids within the composite blade structure that are strategically positioned to initiate controlled delamination when a bird strike occurs. This preliminary action creates predetermined failure zones that prevent uncontrolled disintegration of the entire blade, thereby maintaining structural reliability while using lightweight composite materials.
Solution Approach 2:
The patent changes the structural parameters of the composite blade by incorporating voids with specific geometries and distributions. These voids alter the material's response to impact forces, transforming the failure mode from catastrophic disintegration to controlled delamination, thus improving reliability without sacrificing the weight benefits of composite materials.
2Strength
If the trailing edge is reinforced to prevent whiplash disintegration, then blade strength is improved, but aerodynamic efficiency is compromised due to increased thickness
Solution Approach 1:
The patent applies local quality by placing voids specifically in regions where delamination is most beneficial for preventing whiplash disintegration, rather than uniformly reinforcing the entire trailing edge. This localized approach provides necessary strength where needed while maintaining the aerodynamic profile in critical flow regions.
Solution Approach 2:
The patent accepts that the trailing edge may suffer controlled, localized damage (delamination) during bird strike, rather than preventing all damage through heavy reinforcement. This controlled 'sacrificial' approach protects the main blade structure while allowing the trailing edge to absorb impact energy through predetermined failure modes.
3Strength
If metal capping is added to the trailing edge, then blade strength is improved, but weight balance is compromised
Solution Approach 1:
The patent uses composite material structures with embedded voids instead of adding metal capping. The voids are integrated within the composite laminate structure, maintaining the blade's composite construction and weight balance while providing the necessary strength and controlled failure characteristics to resist whiplash disintegration.
4Reliability
If the blade structure is made stiffer to prevent disintegration, then reliability is improved, but the ability to absorb strain energy is reduced
Solution Approach 1:
The patent converts the harmful effect of bird strike energy into a beneficial controlled delamination process. The voids are positioned to absorb and dissipate impact energy through controlled failure, transforming the harmful kinetic energy from bird strike into a controlled energy dissipation mechanism that protects the main blade structure while maintaining reliability.
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
These solutions effectively inhibit deformation pulse propagation, reduce the risk of disintegration, and maintain aerodynamic efficiency while allowing for controlled material loss and potential self-repair, ensuring the blade remains operational and balanced during extreme conditions.
Implementation Method 1
a strike such as that with a bird leads to a whiplash motion at the trailing edge of the blade
Implementation Method 2
composite material having voids configured to act as crack initiation points when subject to deformation wave
Data Source
AI summary
Blades for gas turbine engines which are formed from composite materials have problems with respect of resistance to impacts such as bird strikes. Previous blades formed from metals had some ductility towards the trailing edge which could accommodate the whiplash effects of impacts. With regard to composite materials such ductility is not present. By providing projections 32 which act as propagation wave trips as well as high intensity reflectors 36 it is possible to limit the whiplash at the edge 31 resulting in damage. Typically a cladding cap 38 is provided which also may be formed from a metal to allow some greater uniformity with respect to mass per length despite the tapering of the blade. Furthermore by providing voids which act as delamination initiation sites cracking can be provided between plies which allows greater flexibility towards the edge and therefore release of energy. These voids may incorporate uncured polymer matrix to act as a binder subsequent to delamination.