Numerical simulations of large-scale turbulence ingestion by a forward flight propellera)

The growing demand for urban air mobility necessitates the development of quieter and more efficient electric vertical takeoff and landing aircraft. This study presents numerical simulations of large-scale turbulence in the wake of a cylinder being ingested by a propeller in forward flight. The computational fluid dynamics solver SIMULIA PowerFLOW is employed to investigate both the flow field dynamics and aeroacoustics of the configuration, and the numerical setup mirrors an earlier experimental campaign, providing validation to the current numerical framework. The results demonstrate that turbulence ingestion leads to a significant increase in the far-field broadband noise components from mid to high frequencies. Interestingly, multiple tonal side-peaks emerge around the fundamental blade passing frequency as a result of the interaction between the propeller and shed vortices from the cylinder, partly attributed to the non-linear turbulent mixing. Flow field results reveal that the significant blade-turbulence interaction modifies the flow downstream of the propeller, particularly a rapid turbulent mixing between the turbulent inflow and the tip vortices, intensifying the asymmetric unsteady loading on the blade. Noise source decomposition identifies the leading edge as the dominant contributor to tonal noise and the broadband component in low-to-mid frequencies, while sources from the trailing edge become significant at higher frequencies.