High-fidelity simulations of noise induced by time-harmonic gust interaction with eVTOL rotor

This study investigates the aeroacoustic effects of harmonic gust disturbances on a five-blade electric Vertical Take-off and Landing Aircraft (eVTOL) rotor in edgewise flight. Delayed Detached Eddy Simulations (DDES) using OpenFOAM, coupled with a synthetic gust generator, are first validated against experimental results for uniform inflow conditions. The results show good agreement for broadband spectra and performance metrics, with slight underprediction of tonal levels near the blade-passing frequency (BPF). In the next step, the gust of 10% fluctuations relative to the freestream velocity is added to the flow with a frequency of 119 Hz (0.357 BPF). Increasing gust intensity to 30% of the freestream velocity has a negligible effect on mean thrust but raises root mean square (RMS) thrust fluctuations by 14%, compared to 3.9% for the gust with intensity of 10% case. Spectral analysis reveals BPF harmonic increase of 16% and 29% for the intensity of 10% and 30% gusts, respectively, while the gust-frequency response is attenuated. Acoustic results show spatially dependent changes, seen in directivity maps: small gust amplitude enhances BPF levels at most microphones, whereas larger amplitude redistributes noise, broadening high SPL regions but reducing peaks in some directions. Overall Sound Pressure Level (OASPL) shifts range from about −2 to +2 dB, depending on position, indicating that higher gust magnitudes primarily alter noise directivity rather than uniformly amplifying it. These findings highlight the importance of considering high-intensity gusts in vertiport noise assessment and support design strategies for eVTOL operations in gust-prone urban environments.