Gas Turbine Intake Liner Splice Design for Acoustic Absorption
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Solution Overview
Problem
Splices between acoustic absorption segments of gas turbine engine liners reduce the effectiveness of fan tone acoustic field absorption by scattering modes that are attenuated less well, making zero-splice liners more desirable but expensive and difficult to manufacture and maintain, especially for larger engines.
Innovation Solution
A gas turbine engine design featuring splices with a first portion of reduced width near the fan and a second portion of increased width further away, minimizing scattering of the fan tone acoustic field while maintaining structural integrity, by ensuring the first portion's minimum width and length allow only cut-off modes to propagate, reducing scattering and enhancing absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If splices are used between liner segments, then manufacturing and maintenance become easier, but acoustic absorption performance deteriorates due to scattering
Solution Approach 1:
The splice is designed with a first portion having reduced width specifically at the location where it intersects the acoustic field path. This local modification minimizes scattering of acoustic modes while the rest of the splice structure maintains its load-bearing function. The reduced width portion allows cut-off modes to propagate without significant scattering, preserving acoustic absorption performance while retaining the manufacturing advantages of segmented liners.
2Reliability
If zero-splice liners are used, then acoustic absorption performance is improved, but manufacturing and maintenance become more difficult and expensive
Solution Approach 1:
Rather than eliminating splices entirely (which would be required for zero-splice liners), the invention applies a local quality modification only to the critical region. The first portion of the splice has reduced width where it intersects acoustic modes, while the second portion maintains normal width for structural integrity. This allows the liner to be manufactured in segments with splices, combining the acoustic performance接近零拼接 liner with the manufacturing advantages of segmented construction.
3Strength
If splice width is increased, then structural integrity is improved, but acoustic scattering increases
Solution Approach 1:
The splice structure is differentiated into two portions with different width characteristics. The first portion has reduced width to minimize acoustic scattering and allow cut-off modes to propagate. The second portion has increased or normal width to provide sufficient structural integrity for joining liner segments. This spatial differentiation of width allows both acoustic performance and structural strength requirements to be satisfied simultaneously.
Solution Approach 2:
The solution addresses the width-scattering relationship by introducing an axial dimension differentiation. Instead of uniformly reducing width throughout the splice, the invention creates a tapered or stepped transition from reduced width (first portion) to increased width (second portion) along the axial direction. This dimensional transition allows the splice to satisfy both acoustic and structural requirements at different locations.
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 effectively reduces acoustic field scattering, improves absorption of fan tone noise, and simplifies manufacturing, transportation, and maintenance compared to zero-splice liners, while maintaining structural integrity and ease of use.
Implementation Method 1
the liner segments are positioned around the circumference of the engine intake and are designed to absorb a proportion of the fan acoustic field propagating along the intake
Implementation Method 2
Splices between the liner segments reduce the performance of the liner in absorbing the fan tone acoustic field because they cause scattering into modes that are attenuated less well by the liner
Data Source
Figure 1~2
Figure 3
AI summary
A gas turbine engine comprising a fan and an intake liner 30, the liner 30 comprising at least two acoustic absorption segments 32 forming a duct and an axially extending splice 40 at each axially extending interface 38 between segments 32, the splice 40 being located between the segments 32. At least one of the splices 40 comprises a first portion 42 and a second portion 44, the splice 40 having a greater segment 32 separating width in the second portion 44 than in the first portion 42 so that adjacent the first portion 42 the segments 32 are closer together than adjacent the second portion 44. The first portion 42 is nearer to the fan than the second portion 44.