ACOUSTIC FIELD CHARACTERISTICS UAV SCREW

Unmanned aerial vehicles (UAVs) began to be actively used in civil and military spheres. During flight, UAV nodes emit noise into the environment, while the main radiation node is its propeller. In the civilian sphere, the noise of a drone can cause noise irritation in people, and in the military sphere, by registering this noise, it is possible to determine its bearing and destroy the aircraft. The need to get rid of these harmful factors creates the need to calculate the acoustic field of the UAV propeller. The task: to analyze the noises that arise during the operation of the UAV; draw up a methodology for calculating the characteristics of the acoustic field of a UAV propeller; develop a program-methodology for measuring characteristics of the acoustic field of a UAV propeller and conduct measurements; to propose methods of noise reduction from propellers. In the actual work, an analytical review of the designs of modern UAVs was carried out, which made it possible to choose the type of drone for research. They became the FPVRaptor V2, which was specially designed for flights with a camera on board to create videos. In addition, FPV Raptor V2 has good flight qualities. The considered characteristics of the drone and its equipment. The main sources of noise when flying a UAV are its engines and propellers. In addition, noise is generated by the airframe and its equipment due to vibrations caused by the imbalance of assemblies and propellers. Vibrations are caused by the skin of the UAV, loose connections, poorly fixed equipment units. The FPVRaptor V2 UAV uses an electric motor, which is the quietest motor used on a drone. Provided that the parts of the drone are connected tightly and the equipment assemblies are securely fastened, the source of the noise is the propeller. The noise generated during the operation of UAV propellers was analyzed. On the basis of theoretical information on determining the acoustic characteristics of a UAV, a new method of calculating the sound pressure in the acoustic field of UAV propellers was developed. The physical and mathematical models proposed by L. Ya. Gutin were used to create the calculation methodology. The MathCAD program was used for calculations. The program allows you to calculate the characteristics of the acoustic field of the propeller of the drone. Based on the results of the calculations, graphs of the directionality of the acoustic field were constructed. The highest level of sound pressure is observed for the fundamental tone, a lower level for the second harmonic, even lower for the third, and so on. For the fundamental tone, the maximum sound pressure level is 1.9222Pa or 99.655dB, which is observed at angles of approximately 132º and 48º