Variable-Depth Acoustic Liner with Shared Inlet Volumes to Reduce Drag
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Solution Overview
Problem
Conventional acoustic liners used in aircraft to reduce noise incur a significant drag penalty and are costly to manufacture due to their perforated facesheets, which limits their effectiveness in reducing fuel consumption and noise exposure.
Innovation Solution
The development of a low-drag, variable-depth acoustic liner with shared inlet volumes, where multiple chambers share a single inlet volume, reducing the number of openings in the facesheet and thus the drag penalty while maintaining acoustic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a perforated facesheet is used in conventional acoustic liners, then acoustic performance is achieved, but drag penalty increases significantly
Solution Approach 1:
Multiple acoustic chambers share a common inlet volume, merging what would traditionally be separate inlet openings into a single shared region. This reduces the total number of perforations required in the facesheet while maintaining the acoustic functionality of multiple chambers with different resonant frequencies.
Solution Approach 2:
The shared inlet volume serves multiple chambers simultaneously, making a single structural region perform the function of multiple separate inlets. This multi-functional design reduces the overall perforation area while maintaining acoustic performance across different frequency ranges.
2Reliability
If a perforated facesheet is used in conventional acoustic liners, then acoustic performance is achieved, but manufacturing cost increases
Solution Approach 1:
Multiple acoustic chambers share a common inlet volume, merging what would traditionally be separate inlet openings into a single shared region. This reduces the total number of perforations required in the facesheet while maintaining the acoustic functionality of multiple chambers with different resonant frequencies.
Solution Approach 2:
The design extracts and eliminates redundant perforations from the facesheet by having multiple chambers share common inlet volumes. This removes unnecessary manufacturing steps and material removal operations, reducing both cost and production time.
3Reliability
If multiple chambers with different depths are used, then broadband acoustic performance is achieved, but the number of openings in the facesheet increases
Solution Approach 1:
Multiple acoustic chambers share a common inlet volume, merging what would traditionally be separate inlet openings into a single shared region. This reduces the total number of perforations required in the facesheet while maintaining the acoustic functionality of multiple chambers with different resonant frequencies.
Solution Approach 2:
The patent transitions from a two-dimensional array of separate circular perforations to a three-dimensional shared inlet volume structure. This dimensional change allows multiple chambers to access a common inlet region, reducing the number of facesheet openings while maintaining broadband acoustic performance through variable chamber depths.
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 design achieves a significant reduction in liner drag and manufacturing costs, enabling simultaneous reductions in fuel burn and noise, while maintaining comparable acoustic performance to conventional liners.
Implementation Method 1
The core may be in the form of a honeycomb, with the liner core partitioned into or defining multiple chambers. An acoustic chamber typically may have at least one partition or side wall (depending on the chamber profile/configuration), an open end, and a closed end or chamber bottom. Each chamber defines a resonating volume that includes an inlet or inlet volume at its opening and a distal chamber interior.
Implementation Method 2
The perforated facesheet, which is the outermost portion of the liner exposed to the flow and thus, closest to the noise source, serves several purposes. The facesheet protects the core from the harsh environment in the engine, couples the external acoustic field to the resonators in the core, and provides acoustic resistance needed to convert incident acoustic energy to heat.
Data Source
AI summary
Systems and devices of the various embodiments may provide a low-drag, variable-depth acoustic liner having shared inlet volumes. Various embodiments may include a low-drag, variable-depth acoustic liner providing aircraft noise reduction. Acoustic liners according to the various embodiments may be used in engine nacelles and/or on external surfaces of an aircraft to reduce acoustic radiation. Acoustic liners according to various embodiments may provide increased broadband acoustic performance with less drag than conventional liners. Various embodiments may provide an acoustic liner with a reduced open area of the facesheet, and therefore reduced drag of the liner, when compared with conventional acoustic liners.