Bent Cell Acoustic Liners for Turbine Engine Noise Reduction

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Solution Overview

Problem

Conventional acoustic liners for turbine engines are ineffective in reducing broadband noise across a wide frequency range without increasing thickness, which is a concern in limited spaces like the engine core, where thickness reduction is necessary for noise reduction and weight optimization.

Innovation Solution

The design incorporates bent cells and holes between cells to extend effective chamber length without increasing overall height, using ceramic matrix composite materials for high-temperature resistance and weight reduction, and incorporates perforated septa for improved frequency absorption and flow control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If cells are made taller to absorb lower frequencies, then broadband noise reduction is improved, but liner thickness becomes unacceptably large

Engineering Contradiction:

Improvebroadband noise reduction capabilityVSAvoidliner thickness

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent bends the cells away from the acoustic source, transforming the linear height dimension into a curved path that fits within the limited radial space. This allows the effective acoustic path length to be extended without increasing the linear thickness of the liner, resolving the contradiction between broadband absorption capability and acceptable liner thickness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The cells are configured with curved or bent geometries rather than straight lines, allowing the acoustic path to follow a curved trajectory. This curvature enables the cells to achieve longer effective lengths for low-frequency absorption while maintaining a compact overall thickness profile that fits within engine constraints.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of manufacture

If conventional straight cells are used, then manufacturing is simple, but effective chamber length is insufficient for low frequency absorption

Engineering Contradiction:

Improvecell structure fabricationVSAvoideffective chamber length

Core Design Contradiction:

Ease of manufactureVSLength of moving object

Solution Approach 1:

The cells are formed with bent or curved configurations that extend the acoustic path length within the same physical footprint. This curvature approach maintains manufacturability using standard forming techniques while achieving the longer effective chamber lengths needed for low-frequency noise absorption.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Weight of stationary object

If liner thickness is reduced to fit engine core, then weight is reduced, but noise absorption effectiveness decreases

Engineering Contradiction:

Improveliner weightVSAvoidnoise absorption effectiveness

Core Design Contradiction:

Weight of stationary objectVSAdaptability or versatility

Solution Approach 1:

By bending the cells, the patent creates a longer acoustic path within a shorter radial thickness, allowing the liner to maintain weight reduction benefits while preserving noise absorption effectiveness across a broader frequency range.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The curved cell configuration extends the acoustic path length without proportionally increasing the liner's radial thickness or weight, thereby maintaining weight efficiency while improving noise absorption performance.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 approach effectively absorbs a broad range of frequencies, including lower and higher frequencies, while minimizing the liner's height and weight, enhancing noise reduction in turbine engines and improving fuel efficiency by reducing engine size and weight.

Implementation Method 1

increase the effective cell height for lower frequency absorption by bending the cells

Methodology Applied

Scientific EffectAcoustic absorption: Acoustic Absorption

Implementation Method 2

putting holes between two or more cells

Methodology Applied

Scientific EffectAir passage through perforations: Permeation

Implementation Method 3

using ceramic matrix composite materials for high-temperature resistance

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Implementation Method 4

An outer wall of one or more of the plurality of cells includes a perforated septum configured to permit passage of air from an airflow

Methodology Applied

Scientific EffectFluid flow through perforations: Permeation

Data Source

PatentUS10107139B1Acoustic liners for turbine engines

Publication Date: 2018.10.23 UNITED STATES GOVERNMENT ADMINISTRATOR OF NASA

AI summary

An improved acoustic liner for turbine engines is disclosed. The acoustic liner may include a straight cell section including a plurality of cells with straight chambers. The acoustic liner may also include a bent cell section including one or more cells that are bent to extend chamber length without increasing the overall height of the acoustic liner by the entire chamber length. In some cases, holes are placed between cell chambers in addition to bending the cells, or instead of bending the cells.