Turbofan Strut Apparatus Resisting Fan Case Deflection
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Solution Overview
Problem
Turbofan engines face deflection issues due to radially outward air loads, which cause distortion of the core's centerline, leading to undesirable contact between rotating blades and casing structures, affecting tip clearances and engine performance.
Innovation Solution
A strut apparatus is coupled to the fan case of the turbofan engine, extending between the fan case and a deflection-resistant structure like the turbine exhaust case, resisting deflection and maintaining the fan case's alignment with the engine's central axis, thereby reducing distortion and preventing contact between rotating blades and casing structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the fan case is subjected to radially outward air loads, then thrust is generated, but the core centerline deflects and tip clearances are compromised
Solution Approach 1:
A strut is introduced as an intermediary component between the fan case and the core support structure. The strut acts as a mediator to transfer and distribute the radially outward air loads, preventing direct transmission of deflecting forces to the core centerline, thereby maintaining tip clearance precision while allowing thrust generation
Solution Approach 2:
The strut's structural parameters (stiffness, length, mounting positions) are optimized to provide appropriate structural compliance. By adjusting these parameters, the system can accommodate thrust loads while limiting core deflection to maintain acceptable tip clearances under various operating conditions
2Manufacturing precision
If the core is rigidly supported to prevent deflection, then tip clearances are maintained, but the fan case cannot accommodate air loads effectively
Solution Approach 1:
The strut support system provides dynamic adaptability rather than rigid constraint. The strut can elastically deform under load, allowing the fan case to accommodate varying air loads dynamically while the core remains sufficiently supported to maintain tip clearances. This dynamic behavior enables the system to adapt to different operating conditions
3Stability of the object's composition
If additional support structures are added to prevent core deflection, then alignment is maintained, but device complexity increases
Solution Approach 1:
The strut serves multiple functions simultaneously: it supports the fan case against air loads, prevents core deflection to maintain alignment, and provides a pathway for load transfer. By consolidating these functions into a single component rather than adding separate support structures, the solution maintains core alignment without proportionally increasing device complexity
Data Source
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Figure 3A
AI summary
A turbofan engine (20) may comprise an inlet (64) and a fan case (66) coupled to the inlet (64). An engine case (36) may be coupled to the fan case (66) via a vane (70) extending between the fan case (66) and the engine case (36). A strut apparatus (75) may extend from the fan case (66) and limit deflection of the fan case (66). The strut apparatus (75) may comprise a first end (100) proximate the fan case (66), and a second end (102) coupled to at least one of the engine case (36) or a structure for mounting the turbofan engine (20) to an aircraft.