The proliferation on small multi-rotor vehicles has created new regulatory challenges in regard to their aeroacoustic signature. Furthermore, these small urban air mobility vehicles (UAMs) inherit most of the complexities seen in other rotorcraft creating a unique two-problem analysis challenge where both aeroacoustic as well as aerodynamics play equally important roles in the design and optimization process. The flows observed are highly non-linear and unsteady with complex interactions between tip vortices and wakes of multiple rotors and the fuselage. Recent experiments conducted in 2018/2019 at NASA Langley aimed at studying these propulsion-airframe integration challenges and to characterize the broadband noise sources seen on a representative “Straight Up Imaging” (SUI) Endurance Quadrotor model. This animation shows WMLES results for flow over this geometry in forward flight using ScaLES. The WMLES with 366.6 million cells was finished in 24 hours for around 40 revolutions of the blades on a desktop workstation with only 2x NVIDIA 4090 cards. Accurate aeroacoustics data at far-field microphones was obtained on-the-fly during the simulations using the near-field CFD data with the acoustic analogy, enabling fast noise predictions for such complex urban air mobility concepts.
