Acoustic and aerodynamic evaluation of POLIMI tandem propellers in hover and cruise flight conditions within GARTEUR AG26

The present work describes the investigation conducted by the GARTEUR Action Group HC/AG-26 into the acoustic and aerodynamic characteristics of tan- dem propeller configurations, with a focus on the impact of mutual interactions between propellers, which are significant for eVTOL aircraft. Numerical results, obtained through simulations with varying levels of fidelity (from panel methods to computational fluid dynamics), were compared with experimental data from a dual propeller test case developed by Politecnico di Milano. The comparison demonstrated the capabilities and limitations of the various numerical approaches in simulating a challenging test case, characterized by strong unsteadiness and significant viscosity effects. The simulations accurately reproduced the aerody- namic performance losses of the rear propeller and the variations in overall sound pressure level, which are correlated with the interaction with the front propeller’s flow, for both flight conditions (hover and airplane mode) and for the different lateral misalignments between the propeller axes.