Riveted Acoustic Treatment Device for Aircraft Nacelle
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Solution Overview
Problem
Existing acoustic treatment devices for aircraft turbojet nacelles face limitations in effectively reducing noise near the flange A1 due to constraints in placement and fixation methods, which can compromise mechanical and acoustic performance.
Innovation Solution
An annular acoustic treatment device with multiple sections, featuring a sound absorption structure and rivet-type fixing means, is mounted on the outer periphery of the internal shell, allowing closer proximity to flange A1 without overmolding or gluing, enhancing flexibility and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If bonding method is used to attach acoustic treatment device, then acoustic performance is improved, but mounting tabs become larger and device cannot be placed closer to flange A1
Solution Approach 1:
The patent replaces the bonding method with a mechanical riveting system. Rivets provide secure attachment without requiring large mounting tabs, enabling the acoustic treatment device to be positioned closer to flange A1 while maintaining reliable fixation. This mechanical substitution resolves the contradiction between achieving strong attachment and minimizing tab size.
Solution Approach 2:
The patent changes the attachment parameter from chemical bonding to mechanical riveting. This parameter change allows for smaller mounting tabs and closer positioning to flange A1, while still achieving effective noise reduction through the riveted connection system.
2Ease of manufacture
If overmolding method is used to attach acoustic treatment device, then manufacturing is simplified, but bond security is insufficient and mechanical/acoustic performance degrades
Solution Approach 1:
The patent replaces the overmolding bonding process with a mechanical riveting system. Rivets provide guaranteed secure attachment without the uncertainties of curing processes, ensuring both mechanical integrity and acoustic performance while maintaining manufacturing simplicity through straightforward assembly operations.
Solution Approach 2:
The patent uses rivets as simple, replaceable fastening elements that provide reliable attachment without requiring complex curing processes. This approach ensures bond security through mechanical interlocking rather than relying on the variable performance of adhesive bonding.
3Ease of manufacture
If single-piece acoustic treatment device is used, then manufacturing is simpler, but flexibility and robustness under mechanical stress are reduced
Solution Approach 1:
The patent divides the acoustic treatment device into multiple sections that can be separately manufactured and then assembled. This segmentation allows each section to be optimized for manufacturing while the assembled structure provides enhanced flexibility and robustness under mechanical stresses produced during nacelle operation.
Solution Approach 2:
The patent creates a dynamic, segmented structure that can adapt to mechanical stresses. The multiple sections allow the device to flex and deform appropriately under load, improving robustness compared to a rigid single-piece construction while maintaining manufacturing simplicity through modular fabrication.
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 noise by allowing precise adjustment of fixing forces and simplifying manufacturing, while maintaining mechanical integrity and reducing mass by avoiding glue usage, thus improving acoustic performance and ease of maintenance.
Implementation Method 1
each section comprising a sound-absorbing structure... arranged to be mounted on an outer periphery of the inner shell so as to absorb acoustic energy
Data Source
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AI summary
The disclosure relates to the field of acoustic treatment for aircraft turbojet engine nacelles. More specifically, it concerns an acoustic treatment device (6) in the form of an annular ring comprising several sections (61-66), each section comprising a sound absorption structure (601), an outer skin (602) and two lateral skins (603, 604) attached to the inner air inlet shroud (302) of such a nacelle by riveting, these sections (61-66) being connected to each other by battens (71-76).