Investigation of Aerodynamic and Aeroacoustic Performance of Various Distributed Electric Propulsion Configurations

This study aims to experimentally and numerically investigate and compare the aerodynamic and aeroacoustic characteristics of four leading-edge mounted Distributed Electric Propulsion (DEP) configurations under different angles of attack. The aerodynamic performance of individual propeller positions and wings is studied and compared experimentally. Numerical simulations using Vortex Particle Method (VPM) are performed to compare with the experimental results and provide aeroacoustic analysis of different configurations. The test rigs are designed and tested in the Wind Tunnel Laboratory at the University of Bristol. The baseline configuration is set as the 12-12-12 propeller DEP with three identical 12-inch propellers. The 12-12-15 and 15-12-12 configurations replace the outboard and inboard 12-inch propellers with a 15-inch propeller, respectively. The fourth 12-12 configuration includes only two 12-inch propellers mounted at the leading edge of the same wing. The thrust of all configurations is matched to be the same as the baseline configuration. The results indicate that for all three-propeller configurations, the mid propeller produces slightly less thrust than the other two propellers, and the higher the propeller rotational speeds and angles of attack, the larger the difference. The torque required to drive the 15-inch propellers is considerably higher than the 12-inch propellers. The efficiency of the 15-inch propeller is higher than that of the 12-inch propeller under most thrust settings. Wing performance comparisons show that the 12-12 configuration performs the worst among all configurations in wing lift-to-drag ratio at two different propeller rotational speeds. At lower propeller rotational speeds, the baseline configuration yields better lift-to-drag ratio of the wing, while the 12-12-15 configuration takes over at higher propeller rotational speeds. Numerical aerodynamic results illustrate good agreement on thrust predictions, whereas torque predictions can vary significantly with the propeller positions on the wing. Aeroacoustic simulations suggest the 12-12 configuration has around 7 dB higher noise emission than all three-propeller configurations for the 1st BPF, whereas only slight differences are observed between the three-propeller configurations.