Assessment of Transition Model and CFD Methodology for Wind Turbine Flows

Abstract

A detailed evaluation of the predictive capability of a Reynolds Averaged Navier Stokes (RANS) solver with a transition model is performed for wind turbine applications. The performance of the computational methodology is investigated in situations involving attached flow as well as incipient and massive flow separation and compared with experiment. Two-dimensional simulations on wind turbine airfoil sections are seen to qualitatively and quantitatively predict the onset of transition to turbulence and provide significantly improved lift and drag predictions when compared to simulations that assume fully turbulent flow. In three-dimensional wind turbine simulations, detailed validation studies of the integrated loads and sectional pressure coefficient also show definite improvements at wind speeds at which separation is incipient or confined to a small portion of the blade surface. At low wind speeds, for which the flow is mostly attached to the blade surface, and at high wind speeds, for which it is massively separated, the transition model produces similar results to a fully turbulent calculation. Overall, the performance of the transition model highlights the necessity of such models while also pointing out the need for further development.