Fan Ramp Noise Attenuating Structure for Thrust Reverser
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Solution Overview
Problem
Aircraft gas turbine nacelles with thrust reversers face challenges in noise suppression, particularly in the fan ramp section exposed to the bypass airstream during thrust reversing operations.
Innovation Solution
The implementation of a noise attenuating structure on the fan ramp, comprising a stacked perforated layer, base layer, and core layer, which includes honeycomb-shaped substructures, effectively reduces noise within the bypass duct by guiding the bypass airstream and utilizing edge seals and specific configurations to attenuate sound waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise attenuating structure is added to the fan ramp, then noise suppression is improved, but device complexity increases
Solution Approach 1:
The noise attenuating structure is nested within the fan ramp assembly, with the perforated panel, absorption material, and core layer integrated into the existing fan ramp structure. This allows noise attenuation functionality to be incorporated without adding separate external components, thereby improving noise suppression while minimizing increases in device complexity.
Solution Approach 2:
The noise attenuating structure is applied locally to specific portions of the fan ramp where noise generation is most significant, rather than throughout the entire structure. The perforated panel with absorption material is positioned in regions experiencing high acoustic energy, providing targeted noise suppression while reducing overall device complexity compared to full-coverage solutions.
2Object-affected harmful factors
If perforations are added to the fan ramp for noise attenuation, then noise suppression is improved, but structural strength deteriorates
Solution Approach 1:
Perforations are introduced only in specific regions of the fan ramp where noise attenuation is most beneficial, rather than uniformly across the entire structure. The perforated panel is positioned in areas experiencing high acoustic energy levels, allowing noise suppression improvement while maintaining structural integrity in critical load-bearing regions.
Solution Approach 2:
The fan ramp employs a composite structure combining solid material regions for structural strength with perforated regions for noise attenuation. The hybrid design integrates areas of different properties - solid sections provide mechanical strength while perforated sections with absorption material provide noise suppression - resolving the contradiction between strength and noise suppression.
3Manufacturing precision
If the base layer abuts the torque box forward bracket, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The base layer is designed with pre-defined abutment features that align with corresponding features on the torque box forward bracket. By establishing precise alignment interfaces in advance during the design and manufacturing of individual components, the assembly achieves high manufacturing precision while maintaining ease of manufacture through straightforward assembly operations.
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
This solution significantly reduces noise levels within the bypass duct during thrust reversing operations, enhancing the overall performance and reducing noise pollution from the gas turbine engine.
Implementation Method 1
a core layer disposed between the perforated layer and the base layer, wherein the core layer includes a plurality of honeycomb-shaped substructures, each substructure operable to reflect the noise back out of the apertures
Implementation Method 2
a perforated layer including a plurality of apertures, the perforated layer operable to receive an amount of the noise from the bypass airstream and permit the noise to pass through the apertures
Data Source
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AI summary
Aspects of the disclosure are directed to a fan ramp (10) for use in a thrust reverser portion of a nacelle (12) of a gas turbine engine (16), the fan ramp (10) extending circumferentially about an axial fan ramp centerline (62). The fan ramp (10) comprises a fan ramp forward edge (67) disposed proximate an aft end of a fan case (37), the fan case (37) at least partially surrounding a fan section (44) of the gas turbine engine (16). The fan ramp (10) also includes noise attenuating structure (212) at a forward section of the fan ramp (10) forward of a torque box (200).