Turbofan Fan Containment Assembly with Nesting Cavity
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Solution Overview
Problem
Gas turbine engines in civil aviation face challenges in containing fan blades during a Fan Blade Off (FBO) event, leading to significant damage and weight increases due to reinforced casings, which reduce aircraft range and fuel efficiency.
Innovation Solution
A containment assembly for turbofan engines comprising a forward fence, aft fence, fan track liner, intermediate casing member, outer casing, and an annular nesting cavity, with a nesting member potentially made of honeycomb material, designed to capture detached blades and minimize downstream damage while reducing weight and drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reinforced casings and mounting structures are used to contain fan blades during FBO event, then fan blade containment reliability is improved, but engine weight increases substantially
Solution Approach 1:
The patent implements a nested containment structure where an inner containment assembly is positioned within an outer containment assembly. The inner assembly includes a forward fence, aft fence, and nesting cavity that can accommodate a detached fan blade. This nested configuration provides effective blade containment while using material more efficiently, reducing overall weight compared to a single thick reinforced casing.
Solution Approach 2:
The containment system is divided into multiple functional components: forward fence, aft fence, intermediate casing member, outer casing, and nesting cavity. Each component serves a specific function in containing the blade, allowing for optimized design of each element rather than requiring a monolithic reinforced structure throughout.
2Object-affected harmful factors
If reinforced casings are used to meet FBO containment requirements, then downstream damage from debris is reduced, but aircraft range decreases
Solution Approach 1:
The nested containment structure with inner and outer assemblies provides effective debris containment to protect downstream components while using material more efficiently. The inner assembly captures the blade in the nesting cavity, preventing it from reaching downstream components, thereby reducing harmful effects without requiring excessive material that would increase weight and reduce range.
Solution Approach 2:
The detached fan blade is extracted from the main engine flow path and contained within the nesting cavity of the inner assembly. This removes the harmful debris from the downstream environment, protecting other engine components from damage while avoiding the need for extensive reinforced structures throughout the entire engine.
3Strength
If reinforced mounting structures are used to withstand FBO damage, then engine structural integrity is improved, but fuel efficiency decreases
Solution Approach 1:
The nested containment assemblies provide the necessary structural integrity to withstand FBO events while using material more efficiently. The inner and outer assemblies work together to contain the blade, providing strength where needed without the excessive weight of uniform reinforcement throughout the engine structure, thereby maintaining fuel efficiency.
Solution Approach 2:
The containment structure provides enhanced strength and protection specifically at the fan blade containment location rather than uniformly throughout the entire engine. The forward fence, aft fence, and nesting cavity are positioned to address the specific FBO risk area, providing local reinforcement that maintains overall engine structural integrity without unnecessarily increasing weight and reducing fuel efficiency.
Data Source
AI summary
A containment assembly is disclosed for a turbofan engine. The containment assembly comprises a forward fence, an aft fence, a fan track liner, an intermediate casing member, an outer casing member, and an annular nesting cavity. The fan track liner is disposed axially between the forward and aft fences. The intermediate casing member is disposed radially outward of at least a portion of the fan track liner. The outer casing member is disposed radially outward of at least a portion of the intermediate member. The annular nesting cavity is bounded at least in part by the intermediate casing member and the outer casing member.