Effect of Wake Alignment on Turbine Blade Loading Distribution and Power Coefficient

Abstract

This paper describes the use of a lifting line model in order to determine the optimum loading on a marine turbine's blades. The influence of the wake and its geometry is represented though the use of a full wake alignment model. The effects of viscous drag are included through a drag-to-lift ratio. Results for different number of blades and tip speed ratios are presented. Various types of constraints are imposed in the optimization method in order to avoid abrupt changes in the designed blade shape. The effect of the constraints on the power coefficients of the turbines is studied. Once the optimum loading has been determined, the blade geometry is generated for a given chord and camber distributions. Finally, a vortex-lattice method is used to verify the power coefficient of the designed turbines.