有限周期微穿孔波纹板吸声体吸声性能研究
STUDY ON THE SOUND ABSORPTION CHARACTERISTICS OF CORRUGATED MICRO-PERFORATED PANEL ABSORBERS WITH FINITE SIZES
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摘要: 为了推动微穿孔吸声体(MPA)在工程中的实际应用, 本文采用数值仿真方法, 研究了有限尺寸的微穿孔波纹板吸声体的吸声性能. 首先, 基于微穿孔板阻抗理论, 并将平面波谱法和有限元分析方法耦合起来, 构造了微穿孔波纹板吸声体(CMPA)的三维仿真模型, 给出了在声波垂直入射和斜入射工况下, 吸声体声学性能的计算列式; 然后, 应用有限元软件COMSOL, 模拟了有限周期CMPA的吸声性能, 分析了波纹深度和波纹间距与吸声性能之间的关系, 以及声波入射方向对吸声性能的影响; 最后, 为改善吸声体对声波方向的敏感性, 设计了双向波纹状微穿孔板吸声体. 结果表明, 在声波垂直入射和斜入射的工况下, 相对于传统的平直微穿孔板吸声体, 波纹板吸声体具有更好的吸声性能, 包括更高的吸声系数和更宽的有效吸声频带; 双向波纹板吸声体能显著改善单向波纹板对声波入射方向的敏感性, 实现在更大声波入射角范围内的有效吸声, 如当入射声波方位角任意且入射角在0° ~ 45°范围内时, 双向波纹板吸声体, 在500 ~ 2500 Hz范围内的吸声系数都大于0.7, 表现出了优良的吸声性能.Abstract: To promote the practical application of micro-perforated panel absorbers (MPA) in engineering, sound absorption performances of corrugated micro-perforated panel absorber (CMPA) with finite sizes were studied in this paper. First, on the basis of the impedance theory of micro-perforated panel, and through coupling the plane wave spectrum method and finite element analysis method, a three-dimensional CMPA model was constructed, which was composed of 15*15 periods, and a set of mathematical formulas calculating sound performances of the model was given under the conditions of normal incidence and oblique incidence of sound waves. Second, the finite element software COMSOL was applied to simulate sound absorption performance of finite periodic CMPA models consisting of unidirectional or bidirectional corrugated panels. And meanwhile, the relationship between the corrugation depth or corrugation pitch and sound absorption performances was analyzed, and the influence of the sound wave incidence direction on sound absorption performances was explored. Finally, to weaken the sensitivity of the sound absorber to the incidence direction of sound waves, a bidirectional CMPA model was designed, and its sound absorption performance was compared with the unidirectional CMPA. The results showed that, compared with the traditional MPA with flat panels, no matter under the normal incident or oblique incidence conditions, the CMPA has better sound absorption performances, including a higher sound absorption coefficient and a wider sound absorption frequency band; compared with the unidirectional CMPA, the bidirectional CMPA can significantly weaken the sensitivity of the sound absorber to the incidence direction of sound wave, achieving effective sound absorption in a larger range of sound wave incidence angles, for example, for an incident sound wave, when its azimuth angle is arbitrary and its incidence angle varies within 0° ~ 45°, the sound absorption coefficient of the bidirectional CMPA is always greater than 0.7 within 500 ~ 2500 Hz.