An efficient hybrid aeroacoustic method to predict the noise of a ducted coaxial-rotor UAV

Ducted coaxial-rotor UAV is a new concept UAV configuration. Compared with the traditional open rotor UAV, it has the advantages of higher safety, lower noise and smaller size, especially suitable for compact space and low noise scene applications. However, the complexity of the internal flow field caused by the presence of the duct makes it difficult to obtain accurate acoustic results by using the conventional aeroacoustic simulation methods. Based on the theory of duct acoustics and the theory of propeller noise, this paper presents an efficient calculation method of aeroacoustic source suitable for the configuration of a ducted UAV. The aeroacoustic source of a ducted coaxial-rotor UAV independently developed by the current research group is studied, and the duct acoustic mode components excited by the aeroacoustic source of the UAV are obtained. The results show that the distribution of the duct mode excited by the aeroacoustic source of the ducted UAV has a strong correlation with the number of propeller blades, and the main characteristic modes dominate the acoustic source of the UAV.