| 摘要 |
<p>A silencer (2) for an auxiliary power unit of an aircraft comprises an inlet (4), an outlet (6), a housing (8), and a flow channel (10), arranged in the housing, comprising a porous wall material. Between the housing and the flow channel an intermediate space is created that by means of one or several outer partitions (12) is divided into outer cells (14) arranged around the flow channel. Furthermore, there is a central body (20) that comprises a casing (26) that is permeable to gas at least in some regions and that is arranged in the interior of the silencer. The central body comprises inner partitions (22) that divide the central body into inner cells (24). The resonance frequency of the inner cells corresponds to the natural frequency of the first radial mode in a channel formed between the central body and the inner surface of the inlet. In this manner particularly good sound attenuation is achieved with a compact installation space of a silencer.</p> |
