Use of perforated panels as an active control source

The use of active vibration control of a thin perforated panel consisting of a closely packed array of holes to reduce noise radiated from a vibrating structure is examined. The advantages of using a perforated panel are that it allows natural cooling of machinery while providing a high level of noise control and it only requires small control forces on the panel to control the noise from heavy structures. The acoustic interaction between the perforated control panel and the radiating primary structure is shown to be negligible, allowing a simple dual source control arrangement to be considered. This model allows more accurate prediction of controlled sound levels to be made compared to previous models that have assumed constant pressure between the primary structure and perforated control panel. [Work Supported by AESIRB.]