Abstract: A method and device for reducing the noise produced in a turbo-machine by e interaction of the blades of a ring of rotor blades and the vanes of a ring of stator vanes, by the creation of a counter-noise of opposed phase. This is achieved by the injection of a fluid into the flow passage of the machine in which the blades and vanes are located. The injection is carried out through orifices located on stationary parts of the machine and equal in number to the vanes of ring of stator vanes, the flow through the orifices being modulated at the frequency of the noise to be reduced and with a phase difference which increase in an incremental manner from one orifice to the next. The phase of the modulated flows injected through the orifices is simultaneously regulated so that the acoustic waves created by the flows are substantially in opposition, with respect to phase, to those of the noise to be reduced.

Abstract: A method and device for reducing the noise produced in a turbo-machine by e interaction of the blades of a ring of rotor blades and the vanes of a ring of stator vanes by the creation of a counter-noise of opposed phase. This is achieved by the injection of a fluid into the flow passage of the machine in which the blades and vanes are located. The injection is carried out through orifices located on stationary parts of the machine and equal in number to the vanes of rings of stator vanes, the flow through the orifices being modulated at the frequency of the noise to be reduced and with a phase difference which increases in an incremental manner from one orifice to the next. The phase of the modulated flows injected through the orifices is simultaneously regulated so that the acoustic waves created by the flows are substantially in opposition, with respect to phase, to those of the noise to be reduced.

Abstract: A device for reducing the noise generated by the blades of at least one r of rotor blades in a turbo-machine by the production of a counter-noise of opposed phase. This is achieved by injection of jets of fluid under pressure through orifices borne by the rotor located near to the periphery of the blades, and the flow of the fluid is modulated at a frequency which is a whole number multiple of the rotational frequency of the rotor shaft. Regulation of phase of the modulated injected fluid is carried out in such a manner that the acoustic waves generated by the injected fluid are substantially in opposition, with respect to phase, to those of the noise to be reduced.