Sound Absorption Of Perforated Plate Absorber Backed By A Porous Liner

In this paper,absorption of aluminum perforated plate absorber backed by a porous liner is studied.The effect of porous materials on the absorbing properties of perforated plate absorber is investigated and the influences of aperture diameter,perforation rate,panel thickness,cavity depth and porous material thickness for perforated plate absorber are discussed.Firstly,based on the transfer function method absorption coefficients of perforated plate absorber are calculated by the simulations using COMSOL Multiphysics software,and effect of the resonant absorber parameters on absorption is studied..Then absorption coefficients of the resonant absorber are measured in the tube,and they are compared with the simulation results.Finally,the absorption performances of the resonant absorber backed with and without porous materials are compared.The conclusions are as follows:(1)The resonant frequencies of the perforated plate absorber are affected by the parameters,such as a perforation rate,a aperture diameter,a panel thickness,and a cavity depth.Among them,the two key parameters are a perforation rate and a cavity depth,and the resonance frequency is shift to the lower frequency by reducing the perforation rate and increasing the cavity depth.(2)The factors that affect the absorption bandwidth of perforated plate absorber are a perforation rate,an aperture diameter,a panel thickness,and a porous material thickness.The two important factors are the perforation rate and the porous material thickness,and absorption bandwidth is broaden by increasing the perforation rate and the porous material thickness.(3)The maximum absorption coefficients of resonant absorber backed with porous materials are above 0.89,their increases are from 106%to 252%,the resonant frequency is shift to the lower frequency by one 1/3 octave and increases of the bandwidth are three 1/3 octaves.(4)Absorption performances of perforated plate absorb backed by porous materials are coincident with simulations and tests.In the whole frequencies band,the absorption peak number is same and the first peak is dominant.In absorption bandwidth,the absorption coefficient are closer,and far from the first resonant frequency the absorption coefficients are bigger differences in simulations and tests.