Numerical Study of a Small Rotor Interacting with a Generic Wing Using a Transient Solver

This paper presents a numerical investigation of the aerodynamic and aeroacoustic interactions between a small rotor and a flat plate simulating a generic wing in hover at low disk loading and Reynolds number. Simulations were performed using ANSYS Fluent with a Detached Eddy Simulation (DES) approach and the Spalart-Allmaras (SA) turbulence model, across a range of nondimensional rotor-wing spacings. Rotor rotation was modeled using a rotating domain, and far-field noise was predicted via the Ffowcs-Williams and Hawkings (FW–H) acoustic analogy. Numerical results were compared with experimental measurements of rotor thrust, download force on the flat plate, plate surface pressure distributions, and acoustic signatures. The simulations demonstrated good agreement with experimental data, particularly in capturing aerodynamic forces and surface pressure on the flat plate. The observed increase in rotor thrust as it approaches the flat plate is attributed to an upflow generated by recirculating wake structures, as supported by flow streamlines and rotor surface pressure data. However, ANSYS Fluent did not fully capture the influence of the deflected rotor wake along the top plate surface on the acoustic signatures, which tends to eliminate the primary tonal noise and increase broadband noise at low frequencies. This discrepancy is likely due to limitations in the FW–H formulation, particularly its inability to account for the flow velocity at the receivers, as well as challenges in isolating motor noise in the experimental setup. The study offers new insights into the aerodynamic mechanisms governing single rotor-wing interaction, including upflow-induced thrust enhancement and complex wake recirculation, with implications for the design and optimization of next-generation urban air mobility (UAM) tiltrotors.