On the Mechanism of Lateral Asymmetry of Noise Radiation from a Propeller Installed Near a Wing

The effect of lateral asymmetry in the radiation pattern of a propeller installed near a wing is studied. Using a simplified theoretical model of propeller loading noise and its shielding by a half-plane, as well as numerical modeling of the interaction of the propeller with a flat finite plate, it is shown that when the propeller and the scattering surface are close to each other, significant lateral asymmetry of propeller tonal noise radiation in the far field occurs. The mechanism underlying this effect, which accompanies the symmetrical noise directivity of the propeller itself and the symmetry of the scatterer (wing), is associated with the phased summation of the sound field radiated directly by the propeller and the secondary sound field generated on the surface of the wing due to scattering of perturbations (mainly hydrodynamic) created by the propeller on the leading edge of the wing. Thus, the study demonstrated that the presence of lateral asymmetry in the noise radiation pattern inherent in propeller aircraft is a consequence of the interaction between propellers and closely spaced wings.