Aircraft Hinge Assembly With Interleaved Seals for Pressure Bleed Control
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Solution Overview
Problem
Aircraft wing tip devices face aerodynamic penalties such as drag and pressure leakage due to small steps or gaps between the fixed wing and movable wing tip, requiring a seal that is both stiff for flight configuration and flexible for ground configuration, while also being resilient to harsh environments, which is challenging to integrate with complex surfaces like doubly-curved wings.
Innovation Solution
A hinge assembly with interleaved fingers and a seal assembly comprising finger seals and under-seal extensions, where each finger seal has a triangular cross-section and is arranged to tilt away from airflow, and fingertip seals fill recesses, maintaining an aerodynamic profile and sealing contact, while under-seal extensions prevent pressure bleed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat rubber seal is used on a barrel-type hinge assembly, then the sealing function is provided, but the seal is difficult to integrate with complex surfaces such as doubly-curved wing surfaces and the unsupported edge can disrupt airflow
Solution Approach 1:
The seal assembly is segmented into multiple finger seals, each attached to a corresponding finger of the hinge plates. This segmentation allows the seal to conform to complex doubly-curved surfaces while maintaining aerodynamic profile, as each finger seal can be independently shaped and positioned to match the local surface geometry.
Solution Approach 2:
The finger seals are designed with curved surfaces that match the doubly-curved geometry of the wing. Each finger seal has a triangular cross-section and is arranged to tilt away from airflow, creating a smooth aerodynamic profile that eliminates disrupted airflow patterns associated with flat seals on curved surfaces.
2Loss of energy
If the seal is made sufficiently stiff to maintain aerodynamic profile, then drag and pressure leakage are reduced, but the seal becomes less flexible and may interfere with movement between flight and ground configurations
Solution Approach 1:
The finger seals are made of resiliently flexible material that provides local compliance at the sealing interface while maintaining overall structural integrity. Each finger seal can deflect independently to accommodate movement between flight and ground configurations, yet maintains sufficient stiffness when engaged to prevent air leakage and maintain aerodynamic profile.
Solution Approach 2:
The seal assembly transitions from a static flat seal to a dynamic system where finger seals can move relative to each other during configuration changes. The resiliently flexible material allows the seals to adapt their shape and position dynamically, maintaining aerodynamic profile in flight configuration while enabling smooth transition to ground configuration.
3Loss of energy
If interleaved fingers are used to create complex aerodynamic profile, then aerodynamic performance is improved, but gaps between fingers create sealing challenges and potential pressure leakage
Solution Approach 1:
The structural function of the interleaved fingers and the sealing function are merged into a single integrated assembly. The finger seals are attached to the fingers themselves, combining the aerodynamic profile creation with the sealing function in one component system, eliminating gaps between separate structural and sealing elements.
Solution Approach 2:
The finger seals act as intermediary elements between the interleaved fingers of opposite hinge plates. These seals fill the gaps between fingers while maintaining the aerodynamic profile, serving as a mediator that resolves the conflict between structural interlocking and aerodynamic smoothness.
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 parasitic drag and noise, maintains the aerodynamic profile, and prevents pressure bleed by sealing gaps between the hinge plates, ensuring efficient airflow and lift performance across flight and ground configurations.
Implementation Method 1
Each seal comprises a resiliently flexible strip
Data Source
Figure 1~2a
Figure 2b
Figure 3a
AI summary
A hinge assembly 8a for an aircraft component comprises first and second hinge plates 9, 10, each hinge plate comprising a plurality of fingers 13-17. The fingers of the first and second hinge plates are interleaved. A seal assembly 28-32 is provided between at least some of the fingers. The provision of a hinge comprising interposed fingers allows for a hinge assembly having a complex aerodynamic profile to be made, while the sealing function is performed by the seals filling the gaps between the fingers.