FR2874233A1 - Sound wave attenuation system for e.g. heat engine, has semi-sphere diffusing gas/sound or air/sound mixture, where sound waves contained in gas or air reflects inside another semi-sphere for rising in counter-direction of mixture in space - Google Patents

Abstract

The system has a semi-sphere (3) whose external part diffuses gas/sound or air/sound mixture, which strikes each other to compress gas and circulates along an outlet tube (6). Sound waves contained in gas or air circumvents the tube and reflects inside a semi-sphere (2`) for rising in counter-direction of the gas/sound mixture in a space between interior of a semi-sphere (2) and exterior of the semi-sphere (3) towards an emission point.

Description

2874233 -1.-

  The present invention relates to a system for attenuating the sounds contained in the gases or the air of the exhaust outlets of a heat engine or turbine, as well as any apparatus releasing air loaded with sound waves.

  The systems traditionally used to reduce the noise of the exhausts are multiple but for the most part are not sufficiently effective, either by their size or their pressure losses, caused by baffles, restrictions or turbulence.

  The attenuation of the sounds contained in the gases or the air of the exhaust outlets is achieved a first time by their passage between the outside of the half-sphere (3) and the inside of the half-sphere (2) which causes the two flows of gases (or air) to arrive face to face, a part of the sounds bypasses the output tube (6) and is either destroyed by the sound waves opposite or continuous against the opposite direction and goes up between the half-spheres (2) and (3) towards the place of emission. The second possibility of destruction for persistent waves is the passage of gases (or air) in the outlet tube (6). The gases (or air) are pushed towards the outlet by the exhaust pressure, when the sound waves are reflected on the inside of the half-sphere (3) and possibly on the outside of the perforated half-sphere. (4) if it is used. The sound waves return in the opposite direction, are reflected on the inside of the half-sphere (2 '), and then between the two half-spheres (2) and (3) to return to the place of emission.

  2874233 -2- For the system to work properly, the speed of the gases must not exceed the speed of sound. The accompanying drawings illustrate the invention: Figure 1 shows a section of the system of the invention.

  Figure 2 shows in cross section.

  Figure 3 shows the separation of gases and sound waves.

  With reference to these drawings the system comprises: A first subassembly composed of an inlet tube (1) to which is fixed (by welding) a hollow half-sphere (2) inside which is fixed the half-sphere (3) by non-restrictive system of three cylindrical studs (5) assembled by welding on the two half-spheres (2 and 3).

  A second subassembly consisting of an outlet tube (6) optionally widened by deformation or by providing a flared piece on which is optionally fixed (by welding) a perforated or braided hollow half-sphere (4). The half-sphere (2 ') is also welded to the tube (6).

  The assembly of these two subassemblies can be done by welding.

  The system is particularly intended for the treatment of exhaust outlets, either thermal engines or turbines or equipment operating with compressed air.

Claims (5)

-3-CLAIMS   1) System for attenuating the sounds contained in the gases or the air of the exhaust outlets, characterized in that it comprises a hollow half-sphere (3), the outer part of which diffuses the gas / sound mixture or air / sound in a uniform way. Then the mixture meets face to face, the gases are compressed, then back along the outlet tube (6). Most of the sound waves do not follow the gases, their speed is greater they will circumvent the outlet tube and then reflect on the inside of the half-sphere (2 ') to go upstream of the gas mixture / sound in the space between the interior of the half-sphere (2) and the outside of the half-sphere (3) towards the place of emission.   2) Sound attenuation system contained in the gas or air of the exhaust outlets characterized in that it comprises, an outlet tube (6) whose opening is in the axis and at the interior of a half-sphere (3). The gases charged with the remainder of sound waves penetrate into the space between the inside of the half-sphere (3) and the mouth of the outlet tube (6). The gases meet and are forced out through the inside of the tube (6), while the sound waves are reflected on the inner face of the half-sphere (3) and emerge from the separation zone and then back up against -Sense to the place of emission.   2874233 -4- 3) System according to claim 1 and 2 characterized in that the outlet tube (6) is of linear cylindrical shape.   4) System according to claim 1 and 2 characterized in that the outlet tube (6) is flared.   5) System according to claim 3 or claim 4 characterized in that the outlet tube (6) is covered or not with a perforated or braided half-sphere (4).