LAGOON: Further Analysis of Aerodynamic Experiments and Early Aeroacoustics Results

This paper presents early results of an experimental aeroacoustic program recently performed in ONERA’s open-jet anechoic windtunnel CEPRA19 with a generic landing gear configuration. This program is the continuation of steady/unsteady flow measurements achieved in 2007 in ONERA’s F2 aerodynamic windtunnel (closed test section). Both experiments constitute the experimental phase of the LAGOON program (LA nding Gear NOise database for CAA validatiON ), currently supported by Airbus and involving ONERA and DLR (the French and German national aerospace research centres) and Southampton University, with the general purpose of evaluate up-to-date CFD/CAA techniques for airframe noise simulation, validated against an extensive experimental aerodynamic/acoustic database. The first point addressed in the present paper is the flow identification between both facilities, relying on limited aerodynamic measurements performed with a 5-hole probe and with onboard static pressure taps and unsteady pressure transducers. This flow identification was supported by a CFD study of the 3D flows in both windtunnels, performed by DLR. It is shown that there exist tiny differences between both flows. The second addressed point is the “signal-to-noise” ratio, or the ratio of the aerodynamic noise radiated by the model, to the background noise measured in the windtunnel without the model. It is shown that this ratio is globally satisfying, especially since this landing gear model with smooth shape is expected to be more silent than an actual landing gear with the same scale.