부산대학교 도서관

In this study, wind tunnel experiments and computational fluid dynamics simulations were conducted to clarify the effects of cross wind on the aerodynamic noise of a multi-rotor drone’s propellers, with and without shrouds. When the propellers were tested without shrouds, the overall sound pressure level (OASPL) of one propeller increased with increasing wind speed, while the OASPL of the other propeller decreased with increasing wind speed. The OASPL might have decreased with an increase in wind speed because the frequency of interference between the blade tip vortices generated from a blade and the following blade was reduced. This can be caused by enhanced downward advection of the blade tip vortices due to increased air flow into the propeller. It is also possible that the intensity of the interference decreased due to enhanced leeward advection of the blade tip vortices. When the propellers were tested with shrouds, the OASPL of one propeller increased and the OASPL of the other one decreased at low wind speeds of 2.0 m/s and 0 m/s. However, the OASPL of both propellers increased significantly at a high wind speed of 10 m/s. This might be because the presence of the shroud prevents the blade tip vortices from being advected to the leeward side and increases the intensity of interference with the following blades.