| 摘要 |
<p>The novel feature of the engine exhaust is that the exhaust (4) pipe (6) comprises at least two telescopic sections (5) with corresponding peripheral acoustic cavities (7), making it possible to vary the length of the pipe (6) and achieve the required level of attenuation of the noise produced by combustion. Extending the sections (5) increases noise attenuation whilst retracting them reduces it, providing an exhaust (4) that adapts to the noise attenuation requirements in force at any given moment. It is fitted to the exhaust of an aircraft APU, designed to have the smallest dimensions of the exhaust (4), improving the aerodynamic properties of the aircraft. Thus, when the aircraft is in flight, when the noise attenuation requirement is lower, the exhaust (4) is kept retracted, whilst when the aircraft is on land it is extended, improving noise attenuation, as is required on land.</p> |
