Fan Case Rubstrip Composite Design for Ice Erosion Resistance
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Solution Overview
Problem
Current fan case rubstrip systems in gas turbine engines experience significant erosion during icing conditions, leading to structural damage and loss of engine thrust due to the sacrificial abradable material wearing away, which also contributes to fan whirl and unbalance issues.
Innovation Solution
A fan case assembly with a rubstrip made of aramid polymer and a septum formed with synthetic fiber material, including protrusions to fill slots and a bumper portion to protect the honeycomb structure, maintains uniform abradable material across the fan blade path and provides additional thickness in areas prone to ice shedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sacrificial abradable material is used in the fan case rubstrip, then fan blade damage is prevented during contact, but the abradable material wears away significantly during prolonged icing, leading to structural damage and loss of engine thrust
Solution Approach 1:
The rubstrip is constructed as a composite structure with multiple layers: an abradable material layer (such as alumina-silica-vermiculite or beryllium oxide) bonded to a durable substrate (such as Inconel 625 or titanium alloy). This composite design allows the abradable outer layer to protect fan blades during contact while the durable substrate resists erosion from ice shedding, preventing both blade damage and material loss.
Solution Approach 2:
The rubstrip design applies different material properties to different regions: the outer abradable layer provides blade protection where contact occurs, while the underlying durable substrate provides erosion resistance in areas prone to ice shedding. This local differentiation of material quality resolves the contradiction between blade protection and erosion resistance.
2Object-affected harmful factors
If the abradable material wears away during prolonged icing, then erosion protection is reduced, but radial clearance at blade tips increases, resulting in loss of engine thrust
Solution Approach 1:
The composite rubstrip structure with durable substrate and abradable coating maintains dimensional stability even when the abradable layer experiences some wear. The durable substrate (Inconel 625 or titanium alloy) prevents excessive material loss, thereby maintaining radial clearance control and preventing engine thrust loss while still providing erosion protection.
Solution Approach 2:
The invention changes the material parameters of the rubstrip substrate to have high erosion resistance and low thermal expansion, ensuring that the radial dimensions remain stable during prolonged icing conditions. This parameter optimization prevents both erosion damage and thrust loss from excessive clearance.
3Reliability
If uniform abradable material is used across the fan blade path, then consistent protection is provided, but additional thickness is required in areas prone to ice shedding, increasing overall rubstrip complexity
Solution Approach 1:
The rubstrip is segmented into distinct functional layers: a uniform abradable material layer for consistent blade protection and a durable substrate layer for structural support and erosion resistance. This segmentation allows each layer to perform its specific function optimally while simplifying the overall design compared to requiring a single thick uniform material.
Solution Approach 2:
The durable substrate serves multiple functions: it provides structural support, resists erosion from ice shedding, maintains dimensional stability, and bonds the abradable layer to the fan case. This multi-functionality reduces the need for additional components and simplifies the overall rubstrip structure while maintaining consistent protection.
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 effectively reduces erosion and maintains engine performance by protecting the underlying structure from ice impingement and erosion, minimizing fan whirl and maintaining thrust efficiency.
Implementation Method 1
The rubstrip may be at least partially formed with an aramid polymer
Implementation Method 2
This solution effectively reduces erosion and maintains engine performance by protecting the underlying structure from ice impingement and erosion
Implementation Method 3
the septum may be at least partially formed with a synthetic fiber material
Data Source
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AI summary
A fan case assembly (60) for a gas turbine engine (20) includes a honeycomb structure (100). The fan case assembly also includes a septum (90) operatively coupled to the honeycomb structure and located radially inward of the honeycomb structure. The fan case assembly further includes a rubstrip (80) in contact with the septum and located radially inward of the septum.