The impact of Reynolds number on two-dimensional aerodynamic airfoil flow

Reynolds number has a direct impact on the performance of a wind turbine aerofoil. In this paper, the airfoil NREL S809 was chosen for the research, using numerical simulation and experiment for the performance of the two-dimensional aerodynamic airfoil flow. While Reynolds number varies from 1.5times104to 2times105, both the drag coefficient and the lift coefficient have great changes. However, while Reynolds number varies from 2times105to 5times106, both the drag coefficient and the lift coefficient have very small changes and become smoother. Details of the flow field and transitional positions at several Reynolds numbers were presented by numerical simulation. The impact on aerofoil force coefficient caused by the changes of Reynolds number was also presented by the experiment. The experimental data validated the results of numerical simulation.