Experimental study of realistic low–noise technologies applied to a full–scale nose landing gear

The landing gear system is the dominant airframe noise source for most modern commercial aircraft during approach. This manuscript reports results from ALLEGRA (Advanced Low Noise Landing (Main and Nose) Gear Regional Aircraft) project. project assessed performance of several highly realistic low–noise technologies (LNTs) applied to a detailed full–scale nose (NLG) model in aeroacoustic wind–tunnel experiments. Four individual concepts tested, namely ramp door spoiler, solid wheel axle fairing, hub caps, multiple perforated fairings. Combinations small variations some these LNTs were also evaluated. use planar microphone arrays allowed application 2D 3D acoustic imaging algorithms assess location strength sources within NLG different emission directions each configuration. axle, inner hubs, steering pinions torque link identified as noisiest elements. fairing was effective LNT, it improved its when combination with spoiler reaching overall reductions more than 4 dBA.