On the rapid noise prediction of multirotor unmanned aircraft systems considering installation effects

For unmanned aerial systems (UASs), rotor operation generates significant noise on the blade surfaces due to complex airflow dynamics, which become even more intricate in the presence of the fuselage. This work presents an efficient noise prediction model for UAS rotors, considering the impact of support structures on unsteady wake flows. The rotor wake is simulated using the free vortex wake method, primarily focusing on the shedding tip vortex characteristics. Consequently, the effects of airframe components on wake vortices are discretely investigated using the surface singularity method. Based on these flow patterns, gust responses on the blades are studied in detail, and the resulting unsteady loading fluctuations are modeled to corresponding sound sources in the acoustic analogy. In the full-length paper, the predicted rotor aerodynamic performance and wake vortex structure with various aircraft layouts will be presented. At the same time, the resulting acoustic index will be compared with high-fidelity numerical calculations for several benchmark cases to validate the framework's accuracy. The proposed noise prediction algorithm is expected to reliably compute the noise emissions of multirotor aircraft under different operating conditions and provide guidance for aircraft design.