Investigation of Sound Absorption Phenomena of Acoustic Liner at High Incident Sound Pressure under Grazing Flow using Aeroacoustics Simulation

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K11926
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 60100:Computational science-related
• Research Institution: Osaka Metropolitan University (2023); Kanazawa Institute of Technology (2021-2022)
• Principal Investigator: Sasaki Daisuke 大阪公立大学, 大学院工学研究科, 教授 (60507903)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 音響ライナ / 空力音響解析 / 乱流解析

Outline of Final Research Achievements

Three-dimensional computational fluid dynamics was conducted under laminar and turbulent flow conditions on an acoustic liner consisting of a single hole, a cell and a resonator to investigate the influence of the hole shape. As a result, it was investigated that the acoustic liner with rectangular holes in the flow field has a lower drag in the flow field than those with square or circular holes. The visualization results revealed that the vortex structures in the cell causes the difference of drag.
In addition, an acoustic propagation simulation was conducted to clarify the sound absorption performance of high-pressure incident sound. As the sound pressure level increased, the sound absorption performance decreased and the resonance frequency changed due to the nonlinear effect.

Free Research Field

数値流体力学

Academic Significance and Societal Importance of the Research Achievements

飛行中等，流れの存在する音響ライナにおいて，乱流の影響が大きく作用することが本研究により明らかとなった．特に，孔形状の変化に伴い，音響ライナ内に流入出する流れが大きく変化し，生成される渦構造も大きく異なる．その結果，音響ライナの抗力も大きく変化することから，音響ライナの吸音性能・抗力等の設計には，乱流解析が不可欠である．
高音圧入射音における解析により，非線形の効果に伴う吸音性能の低下や共鳴周波数の変化が確認できた．そのため高音圧入射音の解析において，直接ナヴィエ・ストークス方程式を解く解析が不可欠である．また，吸音性能の推算には，レジスタンス・リアクタンス等の物性値の高精度な算出が必要である．