Turbofan Inner Ring Reinforcement for Fan Blade Containment
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Solution Overview
Problem
Existing turbofan gas turbine engines face challenges in enhancing the reliability and safety against highly unlikely fan blade out (FBO) events, where a fan blade detaches, potentially causing severe damage due to the blade's forward axial motion.
Innovation Solution
A reinforcing structure is integrated with the inner ring of the fan housing to provide greater impact resistance at the forward end of the radially protruding section, modifying the trajectory of a released fan blade to reduce forward axial motion and enhance containment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fan containment structure is designed to prevent broken fan blades from penetrating engine components, then engine safety is improved, but the containment structure size increases
Solution Approach 1:
The patent applies local quality by providing a reinforcing structure only at the forward end of the radially protruding section where impact resistance is most needed, rather than uniformly reinforcing the entire containment structure. This localized reinforcement maintains safety while minimizing overall structure size and weight.
Solution Approach 2:
The containment structure is segmented into different functional zones: the forward end with enhanced reinforcement for impact resistance, and other areas with standard containment. This segmentation allows optimization of material distribution to achieve safety requirements with reduced overall volume.
2Strength
If the inner ring is reinforced to provide greater impact resistance, then the ability to contain fan blades is improved, but the device complexity increases
Solution Approach 1:
The reinforcing structure is applied locally only to the forward end of the radially protruding section where impact resistance is critical, rather than reinforcing the entire inner ring uniformly. This approach enhances strength where needed while minimizing structural complexity and material usage.
Solution Approach 2:
The reinforcing structure is pre-positioned at the forward end to prepare for potential impact events. This preliminary structural enhancement ensures impact resistance is already in place before any FBO event occurs, simplifying the overall design by eliminating the need for complex active protection systems.
Data Source
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AI summary
Turbofan gas turbine engines and methods are provided. The engines include a fan assembly (104) having an engine rotor hub (110) with fan blades (108) extending radially therefrom configured for rotation of the fan blades, a fan housing structure (206) encircling the fan assembly and including an inner ring (312) that defines an exposed inner surface of the fan housing structure (206) that includes a radially protruding section (314) that defines a recess facing the fan blades (108) and encircling tips (309) thereof, a fan containment structure (310) within the fan housing structure (206) positioned circumferentially around the fan assembly (104) and axially encircling the radially protruding section (314), and a reinforcing structure (420) fixed to or integrated with an annular portion of the inner ring (312) that is configured to provide greater impact resistance to the forward end of the radially protruding section (314) relative to an aft end (418) thereof.