Towards Numerical Aircraft Noise Certification: Analysis of a Full-Scale Landing Gear in Fly-Over Configuration

Abstract

This paper describes a numerical procedure for the prediction of aircraft noise certi cation metrics starting from the aircraft trajectory. The procedure is applied to the nose landing gear of a Gulfstream business jet. The numerical core of the procedure is a hybrid aeroacoustic method based on a lattice Boltzmann ow simulation and a Ffowcs-Williams & Hawkings noise propagation computation. The hybrid method is initially validated by computing the noise generated by a geometrically simpli ed model of the same landing gear installed on a at plate and comparing wall pressure and fareld noise spectra with wind-tunnel measurements. The same numerical method and a similar discretized model are then employed to compute the unsteady ow eld past the real landing gear deployed under the aircraft. The upstream ow conditions are the same occurring during a ight along a \nominally constant descent trajectory at the nearest point to the ground microphone. Comparisons between the predicted noise levels and the measured ones during a ight test, with only the nose landing gear deployed and other airframe and engine sources kept at their admissible minimum, are in good agreement.