Numerical modelling of noise generation by different propeller configurations of a multicopter

Lightweight multicopters (drones) are widely used for commercial and other activities. In the developed countries of Europe and the United States, legislative measures are beginning to be developed to limit the noise of multicopters, so the low noise level of a propeller multicopter is an important factor in competitiveness. This requires the development of computational aeroacoustics methods in combination with computer-aided design systems for drones, including propellers. The application of the method of decomposition of vortex and acoustic modes in a subsonic isentropic flow, described in this article, makes it possible to consider the factors of flow inhomogeneity and rotor interference. For feasibility study, a single-processor version of the software was used, which implements this method in the time domain for the propeller blade passing frequency (BPF). There are presented comparative characteristics of the sound field parameters for different rotor configurations in the hovering mode above the ground. The necessity of optimizing the mutual position of the propellers of the multicopter to ensure a low level of radiated sound power is shown.