Landing Gear Door Segmentation for Wake Noise Reduction
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Solution Overview
Problem
Aircraft noise regulations are not adequately met due to noise generated by the interaction of air turbulence with aircraft structures, particularly during low engine power landings, where the landing gear wake interacts with aerodynamic surfaces, causing significant noise and potential wing flap buffet.
Innovation Solution
A landing gear door design featuring a trailing edge and leading edge section that deploy to reduce flow velocity on the pressure side, with a door flap hinged to deflect towards the landing gear strut, minimizing wake impingement on aerodynamic surfaces and reducing noise through controlled deflection angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the landing gear door is deployed, then the landing gear can be extended, but noise is generated by the interaction of air turbulence with the door structure
Solution Approach 1:
The landing gear door is divided into multiple independent segments: a main door body, a door flap hinged to the trailing edge, and a leading edge section. Each segment can deflect independently to control airflow, allowing the system to maintain deployment functionality while reducing noise through coordinated segment movement.
Solution Approach 2:
The door transitions from a static structure to a dynamic one with movable components. The door flap is hinged to deflect toward the landing gear strut, and the leading edge section is coupled to deflect similarly. These dynamic adjustments allow real-time airflow management to minimize turbulence-induced noise during landing gear operation.
2Object-generated harmful factors
If the door flap and leading edge section deflect toward the landing gear strut, then noise is reduced by minimizing wake impingement, but the structural complexity increases
Solution Approach 1:
The door flap and leading edge section are integrated as part of the landing gear door assembly, sharing common mounting structures and actuation mechanisms. This merging approach allows multiple noise-reduction functions to be achieved through a unified structural design rather than separate components, thereby limiting the increase in overall system complexity.
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 landing gear wake-wing flap interaction noise by 2-5 dB, enhancing wing flap effectiveness and minimizing the risk of unexpected buffet, while meeting noise reduction requirements.
Implementation Method 1
deflects toward a landing gear strut to reduce a local flow speed near the landing gear strut and minimize wake impinging on a pressure side of an aerodynamic surface
Implementation Method 2
minimize wake impinging on a pressure side of an aerodynamic surface
Implementation Method 3
reduces landing gear wake-wing flap interaction noise generated by interaction of a landing gear wake with an aerodynamic surface
Implementation Method 4
interaction of air turbulence with aircraft structures may also be a source of noise
Data Source
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AI summary
A quiet landing gear door 232 and methods are presented. A landing gear door 304 comprises a trailing edge 310 and a leading edge 312 and is operable to deploy to a landing gear door deployed position 314. A door flap 308 comprises the trailing edge and is hinged to the landing gear door. The door flap deflects toward a landing gear strut 322 to a door flap deployed position in response to deployment of the landing gear door. A leading edge section 306 comprises the leading edge and is coupled to the door flap. The leading edge section deflects toward the landing gear strut to a leading edge deployed position in response to deployment of the landing gear door.