Comparing the effect of three transition models on the CFD predictions of a NACA0012 airfoil aerodynamics

The ability to accurately predict transition is important for flows around airfoils, especially at low Reynolds numbers. Transition from laminar to turbulent flow strongly influences the flow separation and the skin friction, thus affecting the airfoil aerodynamic characteristics. In the present work, three models for predicting flow transition were implemented in a 2D curvilinear, aerodynamic Navier-Stokes CFD code. These are Michel's empirical model, the eN model, and a newly proposed transition model (K-V model). The last two models are based on linear stability analysis employing the Orr-Sommerfeld equation to determine the amplification of spatial flow perturbations. The effect of the transition models on the airfoil aerodynamic characteristics at different Reynolds number and incidence angle are studied numerically. Both these parameters, when increased, promote the growth of flow perturbations. The test case is a 2D incompressible, low turbulence air flow around a smooth NACA0012 airfoil. The results of the new K-V transition model are in better agreement with existing experimental data.