Abstract: An internal structure of a primary exhaust duct of a turbomachine. The internal structure comprises a primary wall comprising a surface of revolution, allowing air to pass through the orifices and forming an internal surface of the primary exhaust duct, an interior skin, comprising a surface of revolution, arranged inside the primary wall and extending between an upstream flank for facing toward the front of the turbomachine and a downstream flank for facing toward the rear of the turbomachine, and a plurality of spacers angularly distributed around a periphery of the interior skin and fixed between the primary wall and the interior skin. The particular way in which the interior wall is fixed makes the internal structure easier to construct and allows attenuation of noise at chosen frequencies.

Abstract: A structure which absorbs low-frequency sound comprising a perforated skin, a box having two lateral walls in the shape of a strip, that delimit between them an opening, and a bottom opposite the opening connecting the two lateral walls, the lateral walls becoming closer together with increasing distance from the opening to the bottom. The box is attached to the skin at the opening. Each lateral wall extends width-wise between the opening and the bottom. Each box has two tongues, each tongue being strip shaped, extending lengthwise over an entire box length, and width-wise between the opening and the bottom of the box. Each tongue has a first end attached along an edge of the opening and a second, free end which extends towards the bottom, becoming closer to the second end of the other tongue, where each tongue has an arcuate shape along its length.

Abstract: An internal structure of a primary exhaust duct of a turbomachine. The internal structure comprises a primary wall comprising a surface of revolution, allowing air to pass through the orifices and forming an internal surface of the primary exhaust duct, an interior skin, comprising a surface of revolution, arranged inside the primary wall and extending between an upstream flank for facing toward the front of the turbomachine and a downstream flank for facing toward the rear of the turbomachine, and a plurality of spacers angularly distributed around a periphery of the interior skin and fixed between the primary wall and the interior skin. The particular way in which the interior wall is fixed makes the internal structure easier to construct and allows attenuation of noise at chosen frequencies.