Automatic Transition Prediction in Unsteady Airfoil Flows Using an Unstructured CFD Code

Kurzfassung

An unstructured Reynolds-averaged Navier-Stokes solver, a laminar boundary-layer code and a fully automated local, linear stability code were coupled in order to predict the laminar-turbulent transition in numerical flow simulations. The coupled system was designed to be applied to three-dimensional aircraft configurations of industrial relevance. The transition prediction approach based on the eN-method is now applied to pitching airfoils and the impact of taking into account the laminar-turbulent transition locations in the unsteady simulations on the lift and moment coefficients is investigated. Different transition prediction modes which are available in the coupled system are applied and the influences of the different approaches on the solution are pointed out and compared to each other. Besides some basic tests, the work focuses on the OA209 airfoil in dynamic stall conditions, emphasizing a light stall and a deep stall case. The prediction of the laminar-turbulent transition points and their consideration in the coupled computation is done in a fully automatic manner. In addition, first results from computations using a transition transport model are shown.