Abstract
We present results from an experimental/numerical comparison of energy extraction efficiency and wake flow field characteristics in a small array of three scale-model (45:1) Horizontal Axis Hydrokinetic Turbines (HAHT). The model turbine was designed based on the DOE Reference Model 1 (DOE RM1), with a modified geometry to reproduce performance at the flume scale Reynolds numbers (105 ). These modifications were necessary to overcome the strong Reynolds number dependency of the NACA6xxxx airfoil family, used on the original RM1 design for its cavitation properties, and therefore on the device performance in experimental analysis. The performances and wakes of three turbines placed in a variety of array configurations were analyzed through a combination of experimental measurements and Computational Fluid Dynamics (CFD) modeling. Where possible, the results from experiments and simulations are compared to validate the simulations and understand the limits of the physics captured in the simulations. Once validated, details of the rotor flow field that could not be fully resolved by the experimental measurements are visualized from the numerical solution of the RANS equations to interpret the complex turbine-wake interactions in the experimental results.