FROM EXTERNAL TO INTERNAL NOISE ON AIRBUS A350

摘要

In the beginning of 2018 an important flight test campaign was launched on Airbus A350-1000. The project was to assess the noise for a double purpose : first concerning the noise in forward cabin linked to the engine fan at high rating, then in the aft cabin linked to the engine jet and fan noise. From the external part of the aircraft to the internal noise perceived by the passenger, around 220 sensors were set up on the aircraft. It gathered several kinds of measurements. Thanks to the strong involvement of the flight test and the production teams, this big amount of microphones and accelerometers was set up in less than 7 days during a dedicated working party. First 82 external microphones and 3 accelerometers were installed on the fuselage skin, then 21 accelerometers on the fuselage frames, 4 accelerometers on the cabin floor, 6 microphones between the fuselage and cabin lining, 30 accelerometers on the ceiling, the walls, the hatracks and finally 15 microphones on the seats. In addition the engine rotation speed tachymeter was recorded as well, thanks to a connection from the usual engine monitoring system. A noise localization device made of 60 microphones was installed as well in the forward part of the yankee class of the cabin. In this set of sensors, a very special kind of external flush-mounted microphones were installed on the fuselage. This new prototype was a very thin one. It was able to perform measurements without altering the physical dynamic behaviour of the turbulent boundary layer. The comparison of this sensor outcome with standard flush mounted microphones indicates that the low frequency noise has a lower level.