Application of Prescribed Velocity Methods to a Large-Amplitude Flat-Plate Gust Encounter

Abstract

This paper presents a computational method to study a translating flat plate at steady velocity encountering a sudden transverse gust for different gust magnitudes and airfoil angles of incidence at a low Reynolds number (). An extended split velocity method (SVM) was used to model flat-plate wing/gust encounters in a three-dimensional Navier–Stokes (N-S) solver. The gust velocity in the flow domain was prescribed to the grid points. Source terms were derived analytically from the N-S equations and added to the solver to account for the full interaction between the airfoil and the gust. The effect of the source terms on the results is evaluated for different gust ratios (, 0.4 and 0.8) at fixed-wing incidence angles of 0 and 45 deg. The results using the SVM were compared with those from the field velocity method: a simplification of the SVM that does not include the gust source terms. Inclusion of these source terms was found to be essential to capture the full interaction, especially when the flow was initially separated. In these cases, the source terms reduced the normal force peak and delayed the response when compared to the results without gust source terms. The computational predictions of the aerodynamic forces obtained from the SVM were then compared to experimental measurements. The validation cases focused on a flat-plate wing at a 0 deg incidence encountering an intermediate transverse gust () and a flat-plate wing at 45 deg encountering a large transverse gust ().