Apparatus and method for noise reduction in a transport system for gaseous substances and application of such a device in an exhaust gas system of a ship

摘要

A device and a method for achieving sound reduction within a frequency band in a transport system for gaseous medium, the transport system being arranged between an inlet, which is connected to a sound source, and an outlet. The transport system comprises with a plurality of interconnected channel parts (1-7) and exhibits at least one module (8, 9) comprising at least one reflection attenuator (4) with a resistive length (a2, b2) and at least one reactive attenuator (3) with a reactive length (ai, a3, b1, b3). The resistive length is brought to constitute a quarter of a wavelength of the centre frequency of the frequency band and the reactive length is brought to constitute a quarter of a wavelength of a frequency between, respectively, the lower and upper limit frequencies of the frequency band.