Pages 39-46
An important factor in the design of lifting membrane is the accurate determination of its aerodynamic behavior. Recent studies related to membrane wings or yacht sails have introduced iterative coupling of two numerical approaches, i.e., vortex-lattice method (VLM) and finite-element method (FEM) for analysis of the flow fields and the membrane deflection, respectively. In our previous study, we indicated that VLM is not capable for predicting details of flow including viscous effects and three-dimensional-flow separation, and we presented a numerical approach to predict aeroelastic behavior of lifting membrane in onset viscous flow, where the flow fields are solved by a Reynolds-averaged Navier-Stokes (RaNS) equation method. The fully-elliptic RaNS and continuity equations are solved with a zero-equation turbulence model to provide aerodynamic forces acting on the membrane, and FEM considering large deflection with membrane-finite elements is used for estimating elastic characteristics of the membrane. In this paper, we present some applications of this numerical method. For the accurate determination of its aerodynamic behavior, it is necessary to confirm the several computational conditions in which VLM method could not predict the small differences, and, which are corresponding to the improvement of the sail, i.e., improvements of the sail materials, or, addition of a set of battens.
