Experimental Aeroacoustics Investigation of Interacting Tandem Propellers in Hover

The present paper describes an experimental campaign conducted at Politecnico di Milano within the framework of GARTEUR Action Group HC/AG-26. The campaign deals with the investigation of the aeroacoustic footprint of two propellers models in hovering condition for eVTOL (electrical Vertical Take-Off and Landing) urban air mobility applications. Acoustic measurements were performed by a set of 12 microphones positioned on a circular array surrounding the experimental setup in an anechoic test chamber, while force measurements were performed using load cells integrated into the propeller models nacelles. Test also included flow field measurements using stereoscopic PIV technique. The configurations tested included twin propellers in side-by-side and different staggered configurations with overlap between rotor disks. The test campaign provided a comprehensive database of aeroacoustic measurements for the validation of numerical aeroacoustic codes to be performed in the framework of the GARTEUR Action Group.