Acoustic resonators for noise control in enclosures: Modelling, design and optimization

This work systematically investigates the acoustic interaction between an enclosure and resonators, and establishes systematic design tools based upon the interaction theory to optimize the physical characteristics and the locations of resonators.;A general theoretical model is first established to predict the acoustic performance of multiple resonators placed in an acoustic enclosure of arbitrary shape. Analytical solutions for the sound pressure inside the enclosure are obtained when a single resonator is installed, which provide insight into the physics of the acoustic interaction between the enclosure and resonators. The theoretical model is experimentally validated, showing the effectiveness and reliability of the theoretical model.;Using the validated acoustic interaction model and the analytical solutions, the internal resistance of a resonator is optimized to improve its performance in a frequency band enclosing acoustic resonances. An energy reduction index is defined to conduct the optimization. The dual process of the energy dissipation and radiation of the resonator is quantified. Optimal resistance and its physical effect on the enclosure-resonator interaction are numerically evaluated and categorized in terms of frequency bandwidths. Predictions on the resonator performance are confirmed by experiments. Comparisons with existing models based on different optimization criteria are also performed. It is shown that the proposed model serves as an effective design tool to determine the optimal internal-resistance of the resonator in a chosen frequency band.;Due to the multi-modal coupling, the resonator performance is also affected by its location besides its physical characteristics. When multiple resonators are used, the mutual interaction among resonators leads to the requirement of a systematic optimization tool to determine their locations. In the present work, different optimization methodologies are explored. These include a sequential design approach, the simulated annealing algorithm, and the genetic algorithm. Simulations show that three optimization approaches can all achieve good control performance to different extent. Optimization results reveal the existence of multiple optimal location-configurations of the resonator array. These optimal configurations are verified by experiments. Considering the plural nature of the solutions, engineering design criteria are also proposed.;The feasibility and usefulness of this research is demonstrated in the double-glazed window application.