On the Validity of Blade Response Functions for High Amplitude Vortical Gust

This paper presents several validations concerning the limitations of a classical blade response under varying gust and geometry conditions. The classical blade response function assumes thin aerofoils, linear and small perturbations, and a small angle of attack. However, these assumptions break down for large gust disturbance, where nonlinear effects such as flow separation and stall can occur. This study investigates the unsteady aerodynamic and aeroacoustic responses of blade geometries subjected to vertical gust of varying amplitudes, using both analytical model and CFD simulations. The results enable comparisons between theoretical and extended blade response models, providing validation for the applicability of classical theory across different flow scenarios and geometries. Furthermore, the resulting pressure field is analysed to identify the effects of flow separation and vortex formation during interaction between blade and vertical gust, which influence lift and surface pressure. Lastly, the effects of gust conditions and blade geometries on the radiated acoustic pressure are investigated based on the obtained surface pressure and lift response.