Numerical and experimental study on the suppression of sound radiation from sound source in the duct by MPP

The control of low-frequency ducted fan noise such as in air-handling unit remains a challenging task due to limitation of the space and pressure drop problem. In this study, the micro- perforated panel (MPP) with shallow backed cavities is applied to reduce the noise radiation from the source in the duct. This device is proved to work effectively in the low frequency range. A two- dimensional numerical model has been built up in order to understand the physics behind of sound cancellation, to optimize the panel parameters and to investigate the sound intensity distribution. The numerical result is validated by experiments with a loudspeaker to simulate the sound source, and the measured data matches well with the numerical prediction. The desirable results obtained are beneficial for the design of realistic noise control device in compact configuration in controlling noise inside the air-handling unit.