Design And Analysis Of Labyrinth Acoustic Absorbing Structure

Noise can be recognized when sound exceeds the allowable range of people's life,work or production activities.Especially with the rapid development of industry,transportation and urban construction and the improvement of people's demand for quality of life,more stringent requirements are put forward for noise treatment.Medium and low frequency noise has been paid more and more attention because of its widespread existence in the environment.However,it is difficult for traditional materials or structures to achieve satisfactory results within a certain thickness due to the limitation of mass law.Therefore,how to effectively control the medium and low frequency noise on the premise of guaranteeing a certain thickness of the structure has gradually become the research direction of some scholars.The biggest characteristic of the labyrinth structure is that the folding and winding of space can fully extend the propagation path of sound wave in the structure,which make the distance of sound wave propagation in the labyrinth structure more than ten times or even tens times longer than that in the straight line.The viscous and heat conduction between the sound wave and the medium can effectively attenuate the noise.Firstly,three kinds of labyrinth sound absorption units are designed,which are plane structure,wedge structure and funnel structure.The finite element model of the structure is established according to the sound absorption mechanism of the structure and the relevant boundary conditions.In order to reduce the computational complexity,a narrow area acoustic model is built in the simulation software.The rationality of the relevant settings is verified by the simulation of the model in the literature.Secondly,three kinds of labyrinth sound absorption units are simulated and analyzed.The results show that the shape of the cover plate has a great influence on the sound absorption performance.In comparison,the wedge structure can achieve better sound absorption effect.Therefore,the influence of geometric parameters of wedge structure on sound absorption performance is analyzed.The results show that reducing the size of the through hole of the cover plate,the width of the sound channel or increasing the depth of the sound channel can reduce the center frequency of the wedge structure and increase the peak value of the sound absorption coefficient.Finally,according to the analysis results of the geometric parameters of the front facing wedge structure,the local improvement of the structure is carried out.The variable width structure of sound channel and the structure with perforated plates are proposed.It is found that the two improved structures can increase the peak value of sound absorption coefficient to a certain extent and broaden the sound absorption frequency band.