On a new approach for numerical modeling of the quadcopter rotor sound generation and propagation

The sharp increase in the UAV market for civilian and military purposes shows that the noiselessness and efficiency of a propulsion system with a propeller are key aspects in the development of modern aircraft. At present, quadcopters have become extremely popular and are used for various applications. It should be expected soon that legislation will introduce restrictions on the noise level of UAVs for civilian use. In this regard, the development of theory and computational methods for the effective optimization of the developed UAV propeller is becoming increasingly relevant. Currently, the development of computational methods for determining the amplitudes of pressure pulsations and noise characteristics by numerical modeling of unsteady flow is a necessary requirement for the development of computer-aided design methods for blade machines, where the determining factors are the accuracy and speed of calculations, which can be ensured when the error in calculating the noise spectrum is lower than 2 - 5 dB at a processor time of the order of 1 - 10 minutes per spectrum component. The proposed method based on the acoustic-vortex decomposition of the equations of a compressible medium motion and boundary conditions using the complex acoustic impedance at the boundary of the computational domain and in the rotor-stator interface when solving the acoustic-vortex equation. The determination of the source of acoustic oscillations, the complex acoustic impedance, and the solution of the acoustic equation in complex numbers are tested by experimental and analytical data, including noise generation by the vortex flow around a cylinder and experimental results of measuring pressure pulsations in the air pump model.