Computational Fluid Dynamic Modeling and Analysis of Small Scale Horizontal Axis Wind Turbines

As the demand for wind power grows, the technology used to research and further develop wind power must become more sophisticated. Experiments are expensive and require high end test facilities; a commonly used alternative to experimentation are computational fluid dynamic (CFD) models of wind turbines and wind farms. For this project, Star-CCM+, a CFD software, was used to determine the power generated by small scale horizontal axis wind turbines. The Reynolds Averaged Navier Stokes (RANS) equations were applied to the models in order to solve for the average flow. Though a variety of different types of simulations were used, the focus was on an Actuator Disk Model (ADM) and a Dynamic Fluid Body Interaction (DFBI) model. In the ADM simulation, the wind turbine is modeled as a porous disk in order to simplify the problem and lessen the computation time. This simulation was performed using the Virtual Disk model in Star-CCM+ and applying Blade Element Momentum Theory (BEM). The DFBI simulation is a unique way to model the problem because, unlike ADM, the rotation rate is not set, rather the free stream velocity drives the rotation of the turbine. The DFBI simulation models the wind turbine itself, thus requiring a complicated mesh, called an overset mesh. These two simulations were then validated using experimental data published by the National Renewable Energy Lab and various computational studies.