Acoustic cavity theoretical and numerical analyses for noise attenuation by applying Helmholtz resonators

Resumo

From the passive methods of acoustic cavity sound control, the use of reactive silencers is widely ap-
plied in many engineering sectors. These devices consist of segments of interconnected cavities that do not use

materials with dissipative properties. There is a variety of reactive silencers and the present work has highlighted
the Helmholtz resonator. Methodologies for the evaluation of acoustic cavities using these resonators for sound
control purposes are not extensive, so a theoretical method for the analysis of noise attenuation performance in this
acoustic system is presented. In addition, in order to evaluate and discuss the theoretical results obtained, analysis
was performed using the finite element method with the aid of ANSYS® software with acoustic extension. In

this methodology, the pressure-formulated element has been used. The theoretical and numerical results demon-
strated good agreement and evidenced the sensitivity of the acoustic parameters and sound control efficiency to

the resonator neck geometry which exerted a strong influence on the modal parameters and on the transmission

loss in theoretical results. Lastly, an experimental study of acoustic cavity sound control using Helmholtz res-
onators developed at the University of Brasilia is evaluated by the methodology presented, in order to obtain a

numerical-experimental comparison of the results obtain.