Acoustic response of wing interaction with large-scale vortex gusts

Large-scale vortex gusts generated by complex terrain buildings in urban environments can reach magnitudes comparable to the flight speed of electric vertical takeoff and landing (eVTOL) aircraft, alternating the noise emission property of the rotating wings. In this work, a simplified problem of a straight wing subjected to large-scale vortex gusts is studied in an anechoic wind tunnel, and the acoustic measurements and flow visualization are conducted. The vortex gusts were generated by an upstream pitching aerofoil and captured by time-resolved PIV measurements. The acoustic measurements denote that the gust-induced noise have a hump superposed with several tonal peaks at the low frequency range from 100 Hz to 1000 Hz. The leading-edge noise mainly contributes to the gust-induced noise, while the trailing-edge noise at higher frequency is insensitive to the gusts. The spectral proper orthogonal decomposition of the time-resolved flow field shows that various noise generation processes coexist in the interaction process and produce tonal noise at different frequencies. The understanding of the noise generation process during interaction of large-scale gusts and the wing provides valuable insights into eVTOL noise reduction.