Design, Testing and Numerical Modelling of a Low-Speed Wind Tunnel Gust Generator

Abstract

Understanding and accurately reproducing gust-induced unsteady aerodynamics is essential for improving load prediction, aeroelastic analysis, and control strategies in aircraft, uninhabited aerial vehicles, and wind turbines, particularly in regimes where nonlinear flow phenomena dominate. In this work, a low-speed wind tunnel gust generator based on oscillating vanes is designed, manufactured, and characterised through a combined experimental and numerical investigation. The system is intended to reproduce deterministic gust profiles relevant to aircraft, uninhabited aerial vehicles, and wind-turbine applications, operating in highly unsteady aerodynamic regimes. Experimental measurements using hot-wire anemometry are performed to quantify the generated gust field under a range of free-stream velocities, amplitudes, and forcing frequencies. In parallel, time-accurate CFD simulations are conducted using a deforming-mesh approach to validate the measurements and to analyse the flow physics associated with gust formation and propagation. Particular attention is given to the negative velocity peaks inherent to classical '1-cos' gust profiles. A modified vane motion protocol is proposed and shown to significantly reduce the negative peak factor while maintaining a substantial gust ratio. Numerical results reveal that secondary flow-angle variations arise from nonlinear interactions between vortices shed by adjacent vanes.