Design And Research On Broadband Micro-Perforated Panel Sound Absorption Structure

The micro-perforated panel(MPP)sound absorber has the advantages of good performance at lowfrequency sound absorption,wide application range and no pollution.Although as early as 1975,Maa D Y had proposed the accurate theory of micro-perforated panel sound absorber(MPA).Then,various optimization algorithms have been put forward,but the MPA still has the disadvantages as large structure volume of low-frequency sound absorption and narrow sound absorption bandwidth.Due to the wide distribution range,high noise intensity and wide frequency spectrum of traffic noise and power equipment noise in the environment,it is still very difficult to decline and eliminate such noise.In engineering applications,it is expected that without increasing the volume of the MPA,widen the absorbers’ sound absorption frequency band as much as possible.Therefore,this paper designs a new type of broadband MPA and analyzes its sound absorption characteristics.First,the acoustoelectric analogy approach is briefly introduced,and the accurate theory of the MPA is explained in detail.Secondly,MATLAB is used to analyze the influence of the structural parameters of the MPA on the acoustic characteristics,and the finite element simulation analysis of its sound absorption performance is carried out based on the COMSOL Multiphysics software.In order to improve the sound absorption performance,this paper proposes three new sound absorption structures based on the MPA:cone-shaped micro-perforated panel sound absorber,slit sound absorber and sealed back cavity microperforated panel sound absorber.The finite element method was used to simulate the sound absorption characteristics of these three new sound absorbers.The simulation results show that the sealed back cavity micro-perforated panel sound absorber has a great advantage in performance.Therefore,the absorber was analyzed emphatically,for which the acoustic impedance and sound absorption coefficient calculation method of the absorber were deduced by the acoustoelectric analogy approach,and analyzed the influence of gas parameters on sound absorption characteristics on a theoretical perspective.Finally,the impedance tube method experiment verified the accuracy of the theoretical calculation of the sealed back cavity MPA,and explored the effects of gas in the back cavity,MPP vibration,membrane thickness and back cavity depth on the sound absorption performance.The results show that the gas in the back cavity has a significant impact on the sound absorption performance.When the back cavity is filled with sulfur hexafluoride,the low-frequency sound absorption performance of the absorber is improved,but the sound absorption bandwidth is narrowed;when the back cavity is filled with helium,its normal sound absorption coefficient is greater than 0.5 in the frequency range of 240～4300Hz.The sealed back cavity MPA makes up for the lack of the sound absorption bandwidth of the conventional MPA.In addition,it can also improve the low-frequency sound absorption performance.The sound absorber provides a new choice for engineering applications.