Removable Acoustic Panels With External Recesses

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Solution Overview

Problem

Existing methods for reducing noise emission in turbojet engines, such as using bolted acoustic panels, face issues like structural weakening, risk of screw loss, and difficult maintenance access.

Innovation Solution

Acoustic panels with recesses on their external curved faces that house attachment means, allowing for embedded and locking connections without screws or nuts, optimizing the acoustic coating and facilitating maintenance by minimizing discontinuities in acoustic impedance and ensuring robustness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If acoustic panels are bolted under the casing, then the panels are securely fixed to the casing, but the structure of the casing is weakened by piercings and screws may be lost damaging blades

Engineering Contradiction:

Improvepanel fixation securityVSAvoidcasing structural integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The invention extracts the harmful piercing elements (screws, bolts) from the casing structure by relocating the attachment means to recesses on the external curved face of the panels. The attachment means are contained within recesses that do not open onto the internal curved face, eliminating the need for piercings through the casing while maintaining secure panel fixation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The attachment means are nested within recesses on the panel's external curved face. The recesses house the attachment means internally, allowing secure connection to the casing without extending piercing elements outward that could detach and damage blades.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If acoustic panels are bolted under the casing, then the panels are securely fixed, but maintenance access to bolting locknuts becomes difficult

Engineering Contradiction:

Improvepanel fixation securityVSAvoidmaintenance access to locking mechanisms

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

Instead of opening recesses onto the internal curved face where maintenance access would be difficult, the invention inverts the approach by opening recesses onto the external curved face. This allows maintenance personnel to access and manipulate locking mechanisms from the external side, significantly improving ease of repair while maintaining secure fixation.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If recesses open onto the internal curved face of the panel, then attachment means are easily accessible, but discontinuities in acoustic impedance increase reducing acoustic efficacy

Engineering Contradiction:

Improveattachment means accessibilityVSAvoidacoustic coating efficacy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention inverts the conventional approach by opening recesses onto the external curved face rather than the internal curved face. This maintains accessibility of attachment means for installation and maintenance while preserving the continuity of the internal acoustic surface, thereby maintaining acoustic impedance continuity and maximizing acoustic coating efficacy.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS9932897B2Removable acoustic panels for turbojet engine casing

Publication Date: 2018.04.03 SAFRAN AIRCRAFT ENGINES SAS

AI summary

An acoustic panel intended to be fixed internally to a fan casing of a turbojet engine, including an exterior face and an interior face which are curved about an axis, and two axially opposed transverse faces, the exterior curved face having at least one first recess on the side of a first transverse face and at least one second recess on the side of the opposite transverse face, said recesses each an attachment, in which said recesses do not open onto the interior curved face of the panel. Also covered are the turbojet engine including these panels and the method of mounting them.