Large Eddy Simulation of the Wakes of Three Urban Air Mobility Vehicles

Recent advances in urban air mobility have driven the development of many new VTOL concepts. These vehicles often feature original designs and futuristic shapes. Due to their novelty, the wake characteristics of such aircraft are unknown. However, large wake-induced velocities, should they exist, may be dangerous for any other vehicle evolving in their close proximity. Therefore, improved knowledge about the wakes of VTOL vehicles is needed to guarantee the safety of urban air mobility operations. In this work, we study the wake of three VTOL aircraft in cruise by means of large eddy simulation. We present a two-stage numerical procedure that enables the simulation of long wake ages at a limited computational cost. The analysis of our simulation results reveals that the wakes of rotary vehicles feature larger wake vortex cores than a typical airplane wing. The vortex circulation decay is also faster due to the self-induced turbulence generated during the wake roll-up. Finally, we introduce a model of the vortex circulation distribution that fits the numerical measurements with satisfactory agreement across space and time, and can be used to evaluate induced velocities.