METHOD FOR REDUCING NOISE EMISSION IN THE BACK OF A TURBO-REACTIVE ENGINE AND AN IMPROVED TURBO-REACTIVE ENGINE

摘要

1. A method for reducing noise emissions in the rear of a by-pass turbojet engine for an aircraft, said turbojet engine comprising a nacelle (1) surrounding the front air intake opening (2) and surrounding a cold flow fan (3), a central hot flow generator (4) and a duct (5) a fan with an annular section, in which there is a nozzle (11) for a cold flow, and the specified channel (5) of the fan is formed between an inner fairing (7) surrounding said central generator (4) of hot flow and the inner tubular surface (8) a noise-absorbing casing (9) with an annular cross-section supported by the inner part of the outer fairing (10) of the fan forming the rear part of said nacelle (1), while said casing (9) has a front part (9A) located upstream of said nozzle ( 11) and having an optimal thickness (E) for acoustic attenuation of the noise generated by the specified fan and propagated about the specified cold flow, as well as the rear part (9R) mating with the specified front part (9A) and located on both sides of the throat (12) of the specified nozzle (11), while the specified rear part (9R) of the casing has a thickness that decreases towards the rear end (6) of the specified outer fairing (10) of the fan, limiting the annular outlet for the specified cold flow, and the specified front part (9A) of the casing in the area of its joint with the specified rear part (9R) of the casing has a convergent zone (17D) , in which its inner tubular surface (8A) begins to converge to the specified nozzle (11), characterized in that:! determine to