Far-field level estimation in open wind tunnels with beamforming and CLEAN-SC

This paper presents the estimation of far-field levels in an open wind tunnel of a conventional aircraft half-span model in high-lift configuration at the directivity angles 55◦ , 83◦ , 99◦ , 114◦ , and 136◦ with 3D conventional beamforming and CLEAN-SC with shaded sub-arrays. Reference measurements of the sound pressure level were taken using far-field microphones placed at different distances. The beamforming-based predictions are derived by projecting CLEAN-SC source levels to the far-field, based on the assumption of spatially uncorrelated monopole sources. The estimated far-field sound pressure levels show good agreement with reference measurements at forward and sideward angles, while increasing underprediction is observed at rearward angles due to shear-layer decorrelation.