Investigation of acoustic liner vibroacoustic response and its influence on impedance
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摘要: 声衬在高声压级声波激发下产生声振响应,刚性假设不再成立,其结构振动会对吸声产生一定影响。本文针对振动对声衬吸声的影响和声振响应开展实验研究,通过参数化研究,获得了不同工况和不同穿孔板几何参数下声振响应对声阻抗的影响规律。实验结果表明:穿孔板振动会导致声阻在结构共振频率处出现波峰或波谷,吸声系数出现“额外”的吸声波峰或吸声波谷;穿孔率和声压级的增大会减弱振动的影响,且存在一个临界穿孔率;穿孔板参数会影响高声压级下结构振动导致声阻变化的特征;在结构共振频率附近,小孔–面板速度相位差会发生突变,导致相对速度增大,吸声效果改变。Abstract: The acoustic liners produce vibroacoustic response under the excitation of sound waves at high sound pressure level, and the rigid structure assumption is no longer applied. Their structural vibrations have a certain impact on sound absorption performance. The work presented here is an experimental study on the influence of panel vibrations on sound absorption and vibroacoustic response, and the influence law of vibroacoustic response on acoustic impedance under different perforated plate geometric parameters is obtained through parametric research. The experimental results show that the vibration of the perforated plate causes resistance to the generation of peaks or dips at the structural resonance frequency, and the sound absorption coefficient generates extra absorption peaks or dips that cannot be understood assuming rigid acoustic liners. The increase of the perforation rate and sound pressure level suppresses the influence of vibration, and there is a critical perforation rate. Perforated plate parameters affect the characteristics of resistance changes caused by structural vibration at high sound pressure levels. The phase difference between the small holes and the panel near the structure resonance frequency changes abruptly, resulting in an increase in the relative velocity and a change in the sound absorption performance.
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Key words:
- acoustic liner /
- acoustic impedance /
- vibroacoustic
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表 1 声衬结构参数
Table 1. Summary of liner structure parameters
声衬编号 孔径d/mm 穿孔率σ/% 板厚t/mm 腔深D/mm L1 1 8.4 0.5 50 L2 1 8.4 0.8 50 L3 1 8.4 1.0 50 L4 1 19.6 1.0 50 L5 2 9.4 0.5 50 L6 2 9.4 0.8 50 L7 2 9.4 1.0 50 L8 2 19.6 0.5 50 L9 2 19.6 0.8 50 L10 2 19.6 1.0 50 -
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