Aerodynamic Simulation and Analysis of Multirotor Aircraft
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Beschreibung
In the past decade, multicopter concepts have gained significant importance in industry and research, supported by advances in battery technology. Advantages such as low mechanical complexity, low disk loading, reduced noise, high redundancy, lower pilot workload and improved maneuverability are counterbalanced by more complex aerodynamics. Rotor-rotor interactions typically lead to increased vibrations and reduced efficiency. This work investigates such interactions using a compact 7-rotor configuration as well as the 18-rotor VC2X. The flow solver FLOWer is employed in combination with the flight dynamics tool VFAST.
The 7-rotor configuration consists of a central rotor surrounded by six rotors arranged in a circle. The scenarios examined include hover flight out of and in ground effect (OGE/IGE), descending flights with varying descent rates, and forward flights at 13.9 m/s and 27.8 m/s. For comparison, each rotor is also simulated as an isolated rotor. In OGE hover, the central rotor exhibits an 11% reduction in Figure of Merit, while the outer rotors operate less efficiently. In descent, the vortex ring state appears over a wider range of descent rates. In forward flight at 13.9 m/s , the front rotors gain efficiency, while the rear rotors lose efficiency to a corresponding degree. This effect decreases with increasing speed.
For the VC2X, OGE and IGE hover flights as well as forward flights at 5 m/s, 10 m/s, 20 m/s and 25 m/s are investigated. Comparisons are made between isolated rotors and configurations with and without the airframe. The hover behavior largely resembles that of the 7-rotor setup, although the outer rotors lose efficiency in IGE. The airframe significantly increases wake dissipation.
The differences between isolated rotors and the configurations primarily result from neighboring rotors disturbing each other's inflow, thereby altering the local inflow angle. As speed increases, the pitch angle rises, reducing mutual rotor shading.
Autor*in
Sebastian Miesner
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