Duct Aeroacoustic Control by Multiple Flexible Panels

The flow duct aeroacoustic control method by using a flush-mounted flexible panel has been proven that provides excellent silencing performance for broadband noise. The principle is to utilize the acoustically excited panel vibration to affect the incident noise propagation, reflect the noise to upstream and cause transmission loss in downstream. In addition, the reflection level is able to be promoted by using more than one panel. The performance of the aeroacoustic control by using double panels is studied theoretically and numerically in the present work. A simplified model in frequency-domain is built and solved analytically to resolve the acoustic-structural response when the double panels in the duct are exposed to broadband incident acoustic wave. Besides, to study the aeroacoustic-structural response in the case of the duct carrying flow, a time-domain analysis is conducted by solving the Navier-Stokes equations coupled with the flexible panel dynamic numerically. Since the interaction between two panels is varied with the spacing between them, the spacing is a key parameter that affects the silencing performance. The corresponding variation of the aeroacoustic-structural response with the change of the spacing is investigated. The response under different flow speed is also studied.