초록 ▼

A device (a silencer) for silencing a flow of gas, such as an exhaust gas, comprises at least one acoustic chamber (1, 2, 3) through-flowed by gas, at least one inlet pipe (6) for leading gas into the device and at least one pipe or passage (4, 12, 13) interconnecting two chambers or a chamber and a

A device (a silencer) for silencing a flow of gas, such as an exhaust gas, comprises at least one acoustic chamber (1, 2, 3) through-flowed by gas, at least one inlet pipe (6) for leading gas into the device and at least one pipe or passage (4, 12, 13) interconnecting two chambers or a chamber and an exterior environment or chamber and is designed with such features, including such cross-sectional area transitions between pipes or passages (4, 6, 12, 13) and the chambers (1, 2, 3) that the sound attenuation achieved by the device is high while the pressure drop across the silencer is low and that high attenuation at low characteristic frequencies of flow systems comprising the device are obtained. One or more diffusers (10a, 12a, 13a) for diffusing at least part of the gas flow, e.g., at the inlet to the chambers may be comprised in the device. One or more monolithic bodies or catalyzers may be comprised in the device. Devices with curved or helical passages (FIG. 5) allowing a low natural frequency and embodiments having resonance chambers (FIGS. 10a, b) attenuating at selected frequencies are disclosed. The device may be used for vehicles, including ships or boats and for stationary installations, such as power plants or stationary engines. A method for designing and/or dimensioning the device for a given desired sound attenuation over a given frequency spectrum at given spatial restrictions is disclosed.

대표청구항 ▼

[ What is claimed is:] [1.]1. A device for silencing a gas flow directed therethrough and being adapted for installation in a flow system, said device comprising:a casing,at least one acoustic chamber contained in the casing, said chamber being adapted to have a gas flow therethrough,at least one in

[ What is claimed is:] [1.]1. A device for silencing a gas flow directed therethrough and being adapted for installation in a flow system, said device comprising:a casing,at least one acoustic chamber contained in the casing, said chamber being adapted to have a gas flow therethrough,at least one inlet pipe for leading gas into one of said at least one acoustic chamber,at least one passage of a length L and of a representative cross-sectional area a for leading gas from each one of the at least one acoustic chamber to another of the at least one acoustic chamber or to an exterior environment or an exterior chamber, andat least two transitions of cross-sectional area for the flow of the gas therethrough between a relatively lower cross-sectional area a.sub.i and a relatively higher cross-sectional area A.sub.i, structure of the device, including the above features, being such that the device fulfills the following criteria:(i) the average sound attenuation .DELTA.dB conferred by each transition of cross-sectional area, approximately by the following expression:where n is the total number of transitions of cross-sectional area of the device, A.sub.i is the relatively higher cross-sectional area at the i'th transition of cross-sectional area of the gas flow, a.sub.i is the relatively lower cross-sectional area at the i'th change of cross-sectional area of the gas flow, and k is an empirically determined constant of the value 6.25 dB,is at least2.9 dB when the device comprises no more than two acoustic chamber,1.8 dB when the device comprises three acoustic chambers, and1.1 dB when the device comprises 4 or more acoustic chambers,(ii) the pressure loss over each acoustic chamber expressed as the dimensionless parameter .zeta..sub.j ', defined as the ratio between the static pressure loss over the chamber and the dynamic pressure at a location in said passage leading from the chamber:where .DELTA.p.sub.j is the static pressure loss over the j'th chamber, .rho. is the density of the gas at said location, and u is the mean gas velocity at said location,is at the most 1.5, and(iii) the pressure loss of at least one particular chamber, expressed as the dimensionless parameter .zeta..sub.j ', is at most 0.25.