Noise attenuation features for the casing of a turbo fan engine

摘要

The arm (8B) has a closed cavity, and perforations provided on one of lower surfaces of the connection arm for forming a Helmoltz resonator, where the diameter of the perforations is less than 0.5 mm. The cavity is extended through a pouch shaped hollow element (10) housed in a nacelle surrounding a fan casing and/or extended through a hollow element housed inside a fairing (6) of a primary flow body.