泡沫铝板-二次余数扩散体(QRD)复合吸声体的吸声特性分析

Sound absorption characteristics analysis of aluminum foam plate-quadratic residue diffuser(QRD)composite sound absorber

针对单一泡沫铝多孔板低频吸声性能欠佳的现状,提出了“泡沫铝板-二次余数扩散体(quadratic residue diffuser,QRD)”复合吸声体的吸声结构,这种结构可以较好地兼顾低频和宽带吸声。建立了泡沫铝板-7阶QRD复合吸声体的分析模型,并将模型实体化,在阻抗管中进行正入射吸声系数的试验测量,通过与试验结果的对比验证了分析模型的正确性。基于该模型复合吸声体的多个结构参数变化对吸声性能的影响:分析了QRD背腔的最大深度与QRD阶数对吸声性能影响的规律和原因;设计了三种嵌套式复合吸声体,其中的非对称不等宽度分布嵌套式吸声体具有良好的宽频吸声特性;分析了泡沫铝板的主要结构参数对复合吸声体吸声性能的影响,指出孔隙率的变化对吸声系数有较大影响。

Here,aiming at poor low frequency sound absorption performance of single foam aluminum porous plate,a sound absorption structure of“aluminum foam plate-quadratic residue diffuser(QRD)”composite absorber was proposed,it could take in account both low frequency and broadband sound absorption.The analysis model for the aluminum foam plate-7 th order QRD composite absorber was established,this model was substantialized and experimental measurements for its normal incidence sound absorption coefficient were conducted in impedance tube.The correctness of the analysis model was verified through comparing its analysis results with experimental ones.Effects of multiple structural parameters of this model-based composite absorber on its sound absorption performance were analyzed.Influence laws and reasons of the maximum depth of QRD back cavity and QRD order number on the composite absorber’s sound absorption performance were analyzed.Three nested compound absorbers were designed,and the asymmetric and unequal width distribution nested compound absorber could have good broadband sound absorption characteristics.Effects of main structural parameters of aluminum foam plate on the composite absorber’s sound absorption performance were analyzed to reveal the change of porosity having a larger influence on sound absorption coefficient.