Comparison of predictions and under-the-wing EBF noise data

Abstract

Detailed three-dimensional free field noise data were obtained by NASA for an under-the-wing externally blown model three-flap wing, and for a similar slotless wing. Spatial (polar and azimuthal) and spectral characteristics of these data are presented. These data are compared with predictions from some published EBF noise calculation methods. Methods include the totally empirical ANOPP and GELAC procedures, and a semi-empirical noise component method. The latter method adds the separately computed dipole noise due to fluctuating lift and drag, trailing edge noise, and quadrupole noise due to the deflected jet. Each of these components is calculated for the local geometry and flow conditions.