Numerical study on the aeroacoustics and interaction of two distributed-propulsion propellers in co- and counter-rotations

Abstract

Driven by increasing demands for a sustainable and eco-friendly future in aviation, distributed electric propulsion (DEP) systems have received much attention for their high aerodynamic efficiency. DEP systems of lower noise emissions are desired by customers and policymakers and therefore it is important to understand the aeroacoustics and interaction of distributed propeller systems. In this paper, the aeroacoustics of a simplified DEP system is numerically investigated. The system consists of two Mejzlik 2-blade-9 × 9-inch propellers that are distributed side by side, with a tip-to-tip distance of 10 mm. Their rotating speed and freestream velocity are set as 6500 RPM and 12 m/s, respectively. The configurations of both co- and counter-rotation are considered. Compressible Large-eddy simulations are performed to obtain the flow solutions, and the Ffowcs Williams and Hawkings (FW-H) method is used to calculate the corresponding far-field acoustic solutions. The results present interaction effects for both configurations and compare against isolated propeller results. First, the thrust and the induced sound of each propeller are examined and secondly the impact of the interaction effects on the aerodynamic and acoustic performance is investigated. Finally, sound interference in the acoustic fields is assessed and compared for both co- and counter-rotation configurations.