Theoretical and Experimental Study of Helmholtz Resonator Optimization with Neck Materials
|Course||Power Engineering and Engineering Thermophysics|
|Keywords||Helmholtz resonator Nonlinear efects Sound absorption Forchheimer co-efcient Perforated ceramics|
Helmholtz resonators are widely used as sound absorption devices for their simple aswell as efective sound absorption performance. To improve Helmholtz resonators’ reso-nance sound absorption coefcient and their sound absorption bandwidth simultaneously,sound absorption materials were used to fill the resonators’ neck. In this work, paral-lel perforated ceramics with diferent perforation diameters were installed into the neckof a Helmholtz resonator to improve its acoustic impedance to simultaneously achieve abetter acoustic absorption coefcient and a wider absorption bandwidth. A model of theneck mouth impedance is developed based on the nonlinear Forchheimer relationship. Asystem to measure the static resistivity is used to specify the non-fully developed factorand the Forchheimer coefcient for neck materials with diferent perforation diameters.An experimental system was built to investigate the efect of the perforation diameters onthe sound absorption performance of the resonator. It is found that nonlinear efects nearthe resonance frequency caused by non-fully developed pipe flow cannot be neglected.The experimental results are in good agreement with the theoretical model. Then we gotthe optimal perforation diameter of the neck materials.