Nonlinear Lifting-Line Model using a Vector Formulation of the Unsteady Kutta-Joukowski Theorem

Abstract

In this paper, a vector form of the unsteady Kutta-Joukowski theorem is derived and then used in the formulation of a general Lifting-Line Model capable of analysing a wide range of engineering problems of interest. The model is applicable to investigating lifting surfaces having low to moderate sweep, dihedral, out-of-plane features such as winglets, in both steady-state and unsteady cases. It features corrections of the span-wise circulation distribution based on available two-dimensional aerofoil experimental data, and stable wake relaxation through fictitious time marching. Potential applications include the conceptual and initial design of low-speed Unmanned Aerial Vehicles, the study of flapping flight or Wind Turbine blade design and analysis. Several verification and validation cases are presented, showing good agreement with experimental data and widely-used computational methods.