Research On Acoustic Characteristics Of Incompletely Closed Cavity Structure

Incompletely closed cavities are widely existing structures in the engineering field,and their noise control problems have been plaguing people.Therefore,the analysis of acoustic characteristics of open cavities is a significant research status in the field of engineering,and its research conclusions will provide powerful theoretical support for the acoustic design of complex structures.The acoustic model of the closed cavity and the open cavity are established based on the finite element method and the boundary element method.On this basis,the cavity sound field distribution considering different wall acoustic impedance is analyzed.The topological structure and acoustic characteristics of open cavities with acoustic barriers have been studied in depth.The research contents and results of this thesis are listed below:Based on the three-dimensional wave equation,the sound pressure expression of the point source in the free field is derived.The finite element modeling of the closed cavity and the boundary element modeling of the open cavity are studied.The acoustics under the rigid wall boundary conditions are analyzed.The characteristics,combined with experiments,verify the reliability and correctness of the model.The acoustic cavity model under the impedance boundary condition is established.The acoustic impedance ratio of the wood and wool felt materials are tested based on the impedance tube method.The acoustic characteristics of the polygonal cavity under the two impedance boundary conditions are analyzed.The engineering applicability of this model is verified by experiments.Based on the boundary element method,the acoustic model of open cavity with different topologies is established.The influence of the shape,area,position and quantity of the opening on the acoustic characteristics of the cavity is revealed.The relationship between the sound field distribution of the open cavity and its structural form is analyzed.The acoustic model of the open cavity with obstacles and baffles is established.The influence of the surface acoustic impedance,shape and size of the obstacle on the acoustic characteristics of the open cavity is analyzed.The influence of the quantity of baffles on the acoustic properties and the law of the sound field distribution of the open cavity are studied in depth.This thesis systematically introduces the establishment method of acoustic model of incompletely closed cavity structure,analyzes the acoustic characteristics and influence factors of open cavity in multiple dimensions,and provides an effective analysis method for noise control of open cavity structure.