Large-Cavity Blocker Door Acoustic Structure for Engine Noise
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Solution Overview
Problem
Ultra-high bypass ratio engines require larger nacelles, leading to weight and drag penalties, and compact architectures face challenges in treating acoustic noise due to reduced treatable areas and elevated tonal noise, making it difficult to meet stringent noise standards.
Innovation Solution
A blocker door with a door body, backplate, and structurally-active ribs defining cavities, coupled with a facesheet having perforations to create acoustic cells, which attenuate noise by redirecting airflow and utilizing acoustic features to mitigate elevated tonal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If larger nacelles are used to accommodate increased fan diameters for ultra-high bypass ratio engines, then fuel efficiency is improved, but weight and drag penalties increase
Solution Approach 1:
The blocker door integrates multiple functions into a single component: it serves as both a structural thrust reverser element and an acoustic treatment device. The door body with cavities and the facesheet with perforations are combined into one assembly that simultaneously provides structural support and noise attenuation, avoiding the need for separate acoustic treatment components that would add weight.
Solution Approach 2:
The blocker door is designed to perform multiple functions: it acts as a thrust reverser component, provides acoustic treatment for fan noise, and maintains structural integrity within the compact nacelle. This multi-functionality allows the design to meet multiple requirements without adding separate components that would increase weight.
2Weight of stationary object
If compact nacelle architectures are used to reduce weight and drag, then weight and drag penalties are reduced, but treatable acoustic area is reduced
Solution Approach 1:
The acoustic treatment is applied locally at the blocker door position where fan noise is generated and propagates through the nacelle. By placing acoustic treatment specifically at this critical location rather than distributing it throughout the entire nacelle, the design achieves effective noise treatment within the limited space available in compact architectures.
Solution Approach 2:
The design utilizes the thickness dimension of the blocker door to create cavities, transforming a two-dimensional surface into a three-dimensional acoustic treatment structure. The cavities extend through the door body thickness, providing volumetric acoustic treatment within the constrained lateral space of the compact nacelle.
3Use of energy by moving object
If newer fans are used to improve engine performance, then fuel efficiency is improved, but elevated tonal noise is generated
Solution Approach 1:
The design accepts the elevated tonal noise generated by newer high-bypass fans as an unavoidable byproduct of improved fuel efficiency. The blocker door with its cavity structure is specifically designed to target and attenuate these tonal frequencies, converting the harmful noise into a treatable acoustic problem that can be addressed through resonance-based damping in the cavities.
4Object-affected harmful factors
If more extensive acoustic treatment is applied to meet stringent noise standards, then noise attenuation is improved, but device complexity increases
Solution Approach 1:
The acoustic treatment is merged with the blocker door structure itself. The cavities are formed within the door body, and the facesheet with perforations is integrated onto the same component. This integration eliminates the need for separate acoustic treatment panels or liners that would increase device 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 blocker door effectively reduces aircraft engine noise, meeting new noise standards and reducing landing fees by integrating structural and acoustic enhancements, while maintaining weight efficiency.
Implementation Method 1
a plurality of ribs arranged between the backplate and the facesheet to define a plurality of cavities that communicate with the plurality of perforations to create a plurality of acoustic cells
Implementation Method 2
The blocker door effectively reduces aircraft engine noise, meeting new noise standards and reducing landing fees by integrating structural and acoustic enhancements
Data Source
AI summary
The present disclosure provides a blocker door for a thrust reversing system of an aircraft engine assembly. The blocker door has a door body having a backplate. The blocker door also includes a perforated facesheet coupled with the door body. A plurality of ribs arranged between the backplate and the facesheet define a plurality of cavities that communicate with the plurality of perforations to create a plurality of acoustic cells.