Acoustic performance of different Helmholtz resonator array configurations

This paper presents a theoretical study of the acoustic performance of different Helmholtz resonator (HR) array configurations. A dual HR consisting of two HRs connected in series (neck-cavity-neck-cavity) could be considered as a serial HR array. Two HRs mounted on the same cross-section of the duct constitute a parallel HR array. A lined HR array is composed of two HRs installed on the longitudinal direction of the duct. Since HR is reactive silencer without energy consumption, the energy storage capacity (CTL) of HR arrays could be defined as the area under transmission loss curve. The transfer matrix method is developed to conduct the investigation. The predicted theoretical results fit well with the Finite Element Method (FEM) simulation results. The results indicate that the installation methods have significant effects on transmission loss curves. However, the CTL of the dual HR equals the CTL of each single component HR mounted on the duct in despite of the dual HR having two HRs. The CTL of the parallel HR array is equivalent to the CTL of the lined HR array, which is twice the CTL of the dual HR. The CTL should therefore be considered as one of the main acoustic characteristics of a HR or an array and be taken into consideration in noise control optimization and HR design.