Active multiactuator control of internal noises

Experimentally, we demonstrate the feasability of a device build from the a ssociation of two kinds of actuators, with specific controllers, to activel y control the perturbations generated by internal flows. The reduction of n oise radiated at the exhaust mouth is promising, due to the complementarity of the actuators. One of these, an oscillating frap which motion is synchr onised with the periodic pulsations, is able to control the very low freque ncy peaks and the other; a loudspeaker; is well adapted to actively reduce higher frequencies (harmonics or broad-band noise due to turbulence). (C) 2 000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.