Applications of computational fluid dynamics to a wave energy conversion device

The results of numerical studies of Wells turbine aerodynamics are presented. In the first study, the ability of a hybrid active/passive device to alleviate post-stall buffet of an isolated NACA0012 aerofoil at 18/spl deg/ is evaluated. The passive boundary layer control device is a porous surface/plenum chamber which covers the 1% to 10% chord portion of the aerofoil, and active control is provided by applying suction to the plenum chamber. It is shown that the unsteady load experienced by the solid aerofoil at post-stall incidence is indeed alleviated by the active device; while the passive device has minimal impact on performance at pre-stall angles. The second study uses a three-dimensional numerical method to predict the performance of typical Wells turbines with various numbers of blades and tip clearances. The effect of solidity on turbine performance is predicted well both qualitatively and quantitatively, and the effect of clearance is qualitatively correct.