Unsteady Aerodynamic Response of Rigid Wings in Gust Encounters: Chapter 12– THE INTERACTION OF A SEARS-TYPE SINUSOIDAL GUST WITH A CAMBERED AEROFOIL IN THE PRESENCE OF NON-UNIFORM STREAMWISE FLOW

The unsteady load response of an aerofoil encountering a gust is often modelled using analytical transfer functions, which assume idealised behaviour of both the flow and the aerofoil. One such transfer function is the Sears function, which models a pure transverse gust interacting with a flat-plate aerofoil at zero mean incidence. The function was extended by Goldstein and Atassi to account for camber and incidence as well as the presence of a streamwise gust component. Atassi showed that the effects of camber and incidence (i.e. non-zero mean aerofoil loading) are not negligible when there is a streamwise gust component. In this work, new experimental data is shown for an aerofoil with non-zero loading encountering a gust with both streamwise and transverse components. The data gives validation of the Atassi model. Some of the flow physics behind the Atassi model is also investigated, including the superposition of the gust onto the aerofoil potential field and the propagation of the gust along the aerofoil surface.