Abstract: A silencer for an auxiliary power unit of an aircraft includes an inlet, an outlet, a housing, and a flow channel of a porous material, arranged in the housing. Between the housing and the flow channel an intermediate space is created, which space is divided by at least one outer partition into outer cells arranged around the flow channel. A central body includes a casing that is permeable to gas at least in some regions and that is arranged in the interior of the silencer. The central body includes inner partitions dividing the central body into inner cells. 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.

Abstract: A silencer for an auxiliary power unit of an aircraft comprises an inlet, an outlet, a housing and a flow channel with a porous wall material that is arranged in the housing. An intermediate space is formed between the housing and the flow channel and divided into outer cells that are arranged around the flow channel by means of one or more partitions. This makes it possible to realize a very compact silencer with very good sound insulation properties. The sound dampening can be additionally improved by dividing the outer cells into outer regions and inner regions, by adapting the shape of the silencer to a tail section of an aircraft and by arranging an annular channel on the outlet.

Abstract: A silencer for an auxiliary power unit of an aircraft comprises an inlet, an outlet, a housing and a flow channel with a porous wall material that is arranged in the housing. An intermediate space is formed between the housing and the flow channel and divided into outer cells that are arranged around the flow channel by means of one or more partitions. This makes it possible to realize a very compact silencer with very good sound insulation properties. The sound dampening can be additionally improved by dividing the outer cells into outer regions and inner regions, by adapting the shape of the silencer to a tail section of an aircraft and by arranging an annular channel on the outlet.