Abstract: An engine pod for a gas turbine engine which includes a pod wall having an inside and an outside. The pod wall includes a fixed downstream portion and a displaceable upstream portion which is displaceable in the axial direction between a first upstream position and a second downstream position. At its downstream end facing the fixed portion, the upstream portion forms a radially outer rear edge and axially spaced therefrom a radially inner rear edge, with a recess in between. It is provided that adjacent to the recess, an air-permeable structure is formed in the upstream portion which is intended and configured, in the first upstream position of the displaceable portion, to conduct air flowing in the region of the recess to the inside of the displaceable portion. According to a further aspect of the invention, the axial position of the radially inner rear edge varies in the circumferential direction.

Abstract: An engine pod for a gas turbine engine which includes a pod wall having an inside and an outside. The pod wall includes a fixed downstream portion and a displaceable upstream portion which is displaceable in the axial direction between a first upstream position and a second downstream position. At its downstream end facing the fixed portion, the upstream portion forms a radially outer rear edge and axially spaced therefrom a radially inner rear edge, with a recess in between. It is provided that adjacent to the recess, an air-permeable structure is formed in the upstream portion which is intended and configured, in the first upstream position of the displaceable portion, to conduct air flowing in the region of the recess to the inside of the displaceable portion. According to a further aspect of the invention, the axial position of the radially inner rear edge varies in the circumferential direction.

Abstract: A device for simulating sound produced by certain equipment, for example a rotor-stator arrangement of a turbomachine, or for generation of opposing sound fields for active sound control, including active sound reduction and active sound amplification, comprises flow obstacles (2) provided in a flow duct (1) flown by a fluid at which vortices (5, 6) are shed at a certain frequency depending on the shape and size of the flow obstacles and the velocity of flow. The quantity and spatial arrangement of the flow obstacles is selected such that a periodically spatially and temporally changing pressure field for the excitation of a sound field (8) of a certain modal content is produced by the entirety of the vortices shed. This sound field reacts synchronizingly on the vortex shedding. The resonant circuit so formed, whose vortex shedding frequency is in the range of the resonant frequency of the sound field to be excited, is the sound source.

Abstract: A device for simulating sound produced by certain equipment, for example a rotor-stator arrangement of a turbomachine, or for generation of opposing sound fields for active sound control, including active sound reduction and active sound amplification, comprises flow obstacles (2) provided in a flow duct (1) flown by a fluid at which vortices (5, 6) are shed at a certain frequency depending on the shape and size of the flow obstacles and the velocity of flow. The quantity and spatial arrangement of the flow obstacles is selected such that a periodically spatially and temporally changing pressure field for the excitation of a sound field (8) of a certain modal content is produced by the entirety of the vortices shed. This sound field reacts synchronizingly on the vortex shedding. The resonant circuit so formed, whose vortex shedding frequency is in the range of the resonant frequency of the sound field to be excited, is the sound source.