Validation of a High-Order Large-Eddy Simulation Solver Using a Vertical-Axis Wind Turbine

Abstract

A high-order implicit large-eddy simulation method in two dimensions and three dimensions is used to simulate the aerodynamics of a NACA0012 airfoil over large angles of attack at low chord Reynolds numbers (). The two-dimensional code is found to have adequate agreement with lift and drag experimental data for prestall angles of attack, whereas the three-dimensional code is validated over all angles of attack. The three-dimensional method is able to accurately predict the magnitude and frequency content of the lift and drag forces on the airfoil throughout the range of Reynolds numbers considered in this study. Further comparisons to experimental data are made, including particle image velocimetry vorticity data as well as dye-injection data. As an extension of this application, a section of a constant spinning straight-bladed vertical-axis wind turbine with two blades at a similar Reynolds number is subject to various inflow velocities in two dimensions and three dimensions. The pitch angle of the blades was also varied in order to take into account the uncertainties in the mounting angle of the blade in the experimental studies. As found previously, a small toe-out angle can increase the power absorption of the turbine on the order of 10%. The computed tangential forces as a function of the azimuthal angle agree much better with the experimental data at high tip-speed ratios as compared to other lower-fidelity analytical turbine codes.