Research On Design And Performance Of Ventilation And Sound Insulation Composite Structure

The shielding of acoustic energy is an important research subject in acoustic engineering,which is of great significance in production,life and scientific research.In the case of architectural acoustics,industrial production and electrical and electronic equipment which need noise shielding and heat/air exchange at the same time,traditional materials such as porous sound absorbers based on mass density law cannot achieve sound insulation and ventilation effect at the same time.Acoustic metamaterials generally refer to artificially designed subwavelength size structures that can effectively regulate sound waves and achieve functions that cannot be achieved with traditional materials.Therefore,this paper takes acoustic metamaterials as the research objective,and designs resonant cavity structure based on generalized Snell’s law and coiled path structure based on Fano resonance,so as to achieve the unity of acoustic energy shielding and heat/air exchange function.Firstly,the structure of Helmholtz cavity is designed based on the generalized Snell law.The results show that the tetrad resonant chambers and the double-opened and double cavity series structure can realize the full period(2π)regulation of the acoustic phase and have high acoustic transmission,and can realize the total reflection of the incident acoustic wave near the design working frequency(3000Hz).The loudest transmission loss is about 25 d B,the average sound transmission loss is about15 d B,with about 45% ventilation area.In order to further optimize the exchange efficiency of the metamaterial thermal flow,the coiled path structure is used in Chapter 4 to design the structure based on Fano resonance.The results show that the broadband sound insulation of about 400 Hz can be achieved by means of spatial series arrangement near the structural Fano vibration point,in which the maximum loudest transmission loss can reach 25 d B,and the average sound transmission loss is about 12 d B.The space between the two adjacent structures accounts for about 50%,which can achieve good ventilation effect.Compared with the traditional sound absorption and insulation materials,the phase-gradient-based acoustic metamaterials studied above can not only realize the function of sound insulation and ventilation,but also have no great requirements on the materials,only requiring a higher air impedance mismatch degree.