斜置微穿孔板结构声学特性计算与试验研究

采用声电类比法计算斜置微穿孔板结构吸声性能存在误差.运用阻抗转移法计算斜置结构的吸声系数,用假想平面将斜置微穿孔板结构离散为若干个等宽定空腔的吸声单元,建立简化模型,采用阻抗转移计算每个吸声单元的吸声系数,综合各单元吸声系数,获得整个结构的吸声系数.设计相应的实验比较计算结果表明,采用阻抗转移法计算结果与实验结果吻合良好,声电类比法计算结果偏离实验结果较大.声电类比法采用集中参数分析,需将空腔声阻抗进行近似,造成误差;阻抗转移法不存在这一误差,计算更合理和准确.

The Experiments and Calculation on the Absorptivity of Micro perforated Panel Absorber with Alterable Air cavity

The absorptivity of Micro perforated Panel Absorber (MPA) with the alterable air cavity,calculated by electro acoustic circuit approach (EC),exists the calculation error. The absorptivity is estimated by the impedance transfer method (ITM).The imaginary planes are adopted to divide the MPA with alterable the air cavity into several absorbers with equal width.The absorptivity of each absorber is calculated by ITM after the simplification of the model.By synthesizing the absorptivity of each sound absorption unit, the sound absorption coefficient of the whole structure is obtained.And the corresponding experiments are carried out.A comparison is made with the absorptivity calculated by ITM and EC.It shows that the theoretical results calculated by ITM agree well with experimental results,and is more close to the experimental results than the theoretical results by EC.EC is a kind of concentrated parameter analysis method. This method only considers acoustic compliance,while ignores the effect of acoustic mass.Thus it will cause calculation error.This kind of error does not exist in ITM and TMM,thus their calculations are more accurate than EC.