This paper presents an investigation of the aerodynamic and aeroacoustic interaction of propellers for distributed electric propulsion applications. The rationale underlying the research is related to the key role that aeroacoustics plays in the establishment of the future commercial aviation scenario. The sustainable development of airborne transportation system is currently constrained by community noise, which limits the operations of existing airports and prevents the building of new ones. In addition, the substantial saturation of the existing noise abatement technologies inhibits the further development of the existing fleet, and imposes the adoption of disruptive configurations in terms of airframe layout and propulsion technology. Simulation-based data may help in clarifying many aspects related to the acoustic impact of such innovative concepts. Blended-wing-body equipped with distributed electric propulsion is one of the most promising, due to the beneficial effect of the substantial shielding induced by its geometry. Nevertheless, the novelty of the layout requires a thorough investigation of specific aspect for which no previous experience is available. Herein, the interaction between propellers is analysed for a fixed propeller geometry, as a function of their mutual distance and compared to the acoustic pattern of the isolated one. The aerodynamic results have been obtained using a boundary integral formulation for unsteady, incompressible, potential flows which accounts for the interaction between free wakes and propellers. For the aeroacoustic analyses, the Farassat 1A boundary integral formulation for the solution of the Ffowcs Williams and Hawkings equation has been used. These results provide an insight into the minimum distance between propellers to avoid aerodynamic/aeroacoustic interaction effects, which is an important starting point for the development of distributed propulsion systems.

A numerical methodology for the prediction of vibratory loads arising in wing–proprotor systems is presented. It is applicable to tiltrotor operating conditions ranging from airplane to helicopter-mode flights. The aeroelastic formulation applied takes into account the aerodynamic interaction effects dominated by the impact between\ud proprotor wake and wing, along with the mutual mechanical influence between elastic wing and proprotor blades. A boundary integral formulation suited for configurations where strong body–vortex interactions occur yields the\ud aerodynamic loads, and beamlike models are used to describe the structural dynamics. A harmonic balance\ud approach is applied to determine the aeroelastic solution. In the numerical investigation, first, the aerodynamic solver is validated by correlation with experimental and numerical results available in the literature, then the vibratory loads transmitted by the wing–proprotor system to the airframe are predicted, focusing the attention on the analysis of the different aerodynamic contributions