NOISE CONTROL OF A CHAMBER CORE CYLINDER USING CYLINDRICAL HELMHOLTZ RESONATORS

摘要

Previous investigations have determined that the noise transmission into a finite cylindrical structure at low frequencies is dominated by the cavity resonances. Therefore, noise control at the first several cavity resonances for a Chamber Core cylinder can significantly reduce the noise level at low frequencies inside the cylinder. This work explores the feasibility of noise control for the Chamber Core cylinder using cylindrical Helmholtz resonators. The targeted frequencies are the first four cavity resonances. Detailed considerations of the resonant frequency calculation, resonator design, and experimental verification are presented. The effects on the noise reduction spectrum of two closely spaced resonators are experimentally studied. The optimal position of the resonators is also discussed. The noise control results indicate that the Helmholtz resonators can significantly attenuate the noise level at the targeted frequency bands.