High-fidelity Simulation of the Volocopter-2X in Cruise Flight 

Abstract

A comparison between high-fidelity simulations of a half and a full model approach of the Volocopter-2X (VC2X) in cruise flight is conducted. To ensure an identical flight condition for both cases a flight mechanics trim is performed. Therefore, the computational fluid dynamic (CFD) code FLOWer is loosely coupled to the flight mechanics tool VFAST. The half model simulation setup can save up to half of the cells and therefore also computational time. However, it is only valid for a center of gravity lying on the geometric symmetry plane and a coordinated flight with a zero sideslip angle and no roll rate. The comparison between the half and full model shows no visible difference in the mean rotor revolution speed and only small difference in the pitch attitude. The Volocopter flow is characterized by a high density of small-scale vortex structures. These result, on the one hand, from the rotor wake and rotor-rotor interactions and, on the other hand, from rotor-airframe interactions. A vortex tube developes near the symmetry plane above the rotor disc of the VC2X, which is more prominent in for the half model. The differences on the level of the individual rotors is for most rotors small, only the front outer rotors show bigger deviations.

Experimental Investigation on Thrust Performance of a Small-Scale Staggered Rotor System in Hover

“…Therefore, it is essential to investigate the impact of axial distance to provide insights for the design of coaxial rotorcraft. To characterize the influence of axial distance on rotor thrust at different speeds, we define a thrust variation coefficient ∆T: ∆T = (Tmax − Tmin)/Tave (7) For the same rotor speed and axial distance parameters, Tmax represents the maximum thrust of the bottom rotor at different lateral distances, Tmin represents the minimum thrust of the rotor at various lateral distances, and Tave is the average thrust of all rotor systems. After data processing, the results are presented in Table 2.…”

“…Several conceptual designs or prototypes have been unveiled by manufacturers such as Rolls-Royce [5], Uber [6], Airbus and Volocopter GmbH. Volocopter GmbH has introduced a very promising concept, the VC2X, featuring 18 rotors [7]. Aircraft that are utilized for UAM require outstanding aerodynamic performance which is closely related to their propulsion system [8,9].…”