Development and commissioning of an aeroacoustic test bench for the investigation of single and coaxial propeller noise

This paper describes the design and commissioning of an aeroacoustic test rig for the study of single and coaxial propeller propulsive systems. The size of the propellers matches typical drone applications. The experimental setup, designed and commissioned at the ALCOVES anechoic laboratory of von Karman Institute for Fluid Dynamics, is equipped with aerodynamic sensors for performance analysis and is surrounded by a microphone antenna for the characterization of the noise level and directivity. Thefacility permits varying different parameters such as the longitudinal distance between the rotor planes, and the rotational speed/direction of each propeller. Requirements for the qualification of the test room consist of low-level background noise and minimized turbulence ingestion noise. Two experimental databases have been constituted and are joined to the present paper: (i) for the DJI 9450 two-bladed propeller, verified against data from the literature, and (ii) for single and coaxial contra-rotating Mejzlik two-bladed propellers. The proposed benchmark data will support the validation of low- and high-fidelity numerical methods.