Acoustic Liner Test Platform for Simultaneous Drag and Impedance Measurement

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Solution Overview

Problem

Existing methods for measuring the performance parameters of acoustic liners in aeroengine nacelles are inadequate as they separate drag and acoustic impedance tests, leading to inconsistent conditions and inaccurate data, which hinders comprehensive design in both aerodynamic and acoustic aspects.

Innovation Solution

A comprehensive performance test platform is developed, comprising a flow duct with an acoustic source section and a test section, equipped with loudspeaker arrays, microphone arrays, a drag balance, and strain gauges, allowing simultaneous measurement of stress, drag, and acoustic performance parameters of the acoustic liner under controlled sound intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If drag and acoustic impedance tests are conducted separately, then each test can be performed with dedicated measurement mechanisms, but the experimental conditions cannot be completely consistent leading to inaccurate corresponding data

Engineering Contradiction:

Improvemeasurement accuracy of drag and acoustic impedanceVSAvoidtest system configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines drag measurement and acoustic impedance measurement into a single integrated test system. The flow duct serves as a common test environment where both the drag balance (for drag measurement) and microphone arrays (for acoustic impedance measurement) operate simultaneously. This merging ensures that both parameters are measured under identical flow conditions, incident sound wave conditions, and acoustic liner configuration conditions, thereby resolving the inconsistency problem while maintaining measurement accuracy through dedicated sensing mechanisms for each parameter.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The flow duct is designed as a multi-functional test chamber that simultaneously supports drag measurement, acoustic impedance measurement, and incident sound wave generation. The loudspeaker array integrated into the flow duct walls can generate controlled incident sound waves that affect both drag and acoustic impedance measurements. This universal test platform eliminates the need for separate test setups and ensures that all measurements are performed under consistent and controllable conditions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If the acoustic liner is designed to reduce noise, then noise reduction performance is improved, but aerodynamic drag increases due to surface perforation

Engineering Contradiction:

Improvenoise reduction performanceVSAvoidaerodynamic drag

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

The patent enables systematic investigation of the trade-off between noise reduction and drag by allowing independent variation of key parameters including perforation ratio, hole diameter, liner thickness, and incident sound wave intensity. The integrated measurement system captures how changes in these parameters simultaneously affect both acoustic performance (noise reduction) and aerodynamic performance (drag). This comprehensive parameter space exploration facilitates the design of acoustic liners that optimize the noise-drag trade-off for specific application requirements.

Inventive Principle:

Principle #35Parameter changes

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 platform enables accurate simultaneous measurement of stress, drag, and acoustic performance parameters, overcoming the issue of inconsistent experimental conditions and providing reliable data for integrated acoustic liner design.

Implementation Method 1

the wall surface of the acoustic source section is provided with a loudspeaker array

Methodology Applied

Scientific EffectElectroacoustic transduction:

Implementation Method 2

the wall surface of the test section opposite or adjacent to the measured acoustic liner is provided with a second microphone array

Methodology Applied

Scientific EffectAcoustic pressure detection:

Implementation Method 3

the measured acoustic liner is provided with a strain gauge

Methodology Applied

Scientific EffectStrain measurement:

Implementation Method 4

the interior of the test chamber can be provided with the acoustic liner specimen, acceleration transducer and drag balance

Methodology Applied

Scientific EffectForce measurement:

Data Source

PatentUS11474001B2Comprehensive performance test platform for acoustic liner

Publication Date: 2022.10.18 BEIHANG UNIV

AI summary

The present disclosure relates to the technical field of aerodynamic and acoustic measurement, in particular to a comprehensive performance test platform for acoustic liner. Based on this comprehensive performance test platform for acoustic liner, the stress of the measured acoustic liner under high sound intensity can be measured by using strain gauges arranged on the measured acoustic liner, the aerodynamic drag of the measured acoustic liner can be measured by using the drag balance, and the acoustic performance parameters of the measured acoustic liner can be calculated based on the sound pressure data obtained by the microphone array. With this test platform, the stress, the aerodynamic drag and the acoustic performance parameters of the measured acoustic liner can be measured simultaneously, which overcomes the problem of inaccurate experimental data obtained in inconsistent experimental conditions caused by conventional separate acoustic liner tests.