Patent ID: 7654363

Claim:
A bypass turboengine of an aircraft, the turboengine comprising: a nacelle that delimits the front an air inlet and includes a cold stream fan, a hot stream central generator, and a fan channel with an annular section having a nozzle for the cold stream, wherein: the fan channel is formed between an internal cowl surrounding the hot stream central generator and an internal tubular face of an acoustic attenuation coating with the annular section carried internally by an external fan cowl forming the rear of the nacelle, the coating comprises: a front part, disposed upstream of the nozzle, having an optimal thickness for the acoustic attenuation of the noise produced by the fan and conveyed by the cold stream, and a rear part, contiguous with the front part and disposed on either side of the throat of the nozzle, the rear coating part having a thickness that decreases towards the rear edge of the external fan cowl delimiting an annular ejection orifice for the cold stream, the front coating part has, in the vicinity of its junction with the rear coating part, a convergent zone in which its internal tubular face begins to converge towards the nozzle, a critical zone of the fan channel is defined, beginning at the nozzle throat and extending frontward, in which any possible geometric modification of the fan channel and the internal tubular face of the rear coating part is impossible without a modification of parameters of the nozzle, in the convergent zone of the front coating part, the internal tubular face has a progressive increase in the thickness of the coating towards the rear coating part and this progressive modification in the internal tubular face of the contiguous rear coating part is continued until a zone of the latter with increased thickness is obtained in which the thickness is at least equal to the optimal thickness, and the rear end of the zone with increased thickness is linked to the front end of the critical zone by an internal tubular face with an inflection profile.