An Unsteady Lifting-Line Model
Mark Drela
Department of Aeronautics and Astronautics
MIT
Abstract:
The lifting-line approximation has long been used as an effective and economical quasi-steady aerodynamic model for wings and rotor blades of high aspect ratio. However, it has not been used in fast-unsteady applications such as flutter prediction, for which chordwise resolution of the surface and wake vorticity has been considered essential. The much more expensive lifting-surface methods have been therefore used for these problems.
The talk will present extensions to the simple lifting-line model which enable it to predict fast unsteady airloads with sufficient accuracy to give reliable flutter and gust-load predictions. Extensions for treating flow separation will also be discussed. The great economy of the lifting-model is retained with these extensions, allowing accurate aero/structural predictions of flutter and gust loads to be performed with relatively simple one-dimensional beam models.