FEASIBILITY STUDY OF e~N TRANSITION PREDICTION IN NAVIER-STOKES METHODS FOR AIRFOILS

摘要

When Navier-Stokes methods are applied in the design process for laminar airfoils, the prediction of the transition location still represents an unresolved problem. By the acceptence of the e~N method as representing a convenient transition prediction tool, the requirements for coupling e~N to Navier-Stokes methods will be demonstrated. In particular, the possibility to determine the laminar and turbulent viscous length scales is outlined. Based on the knowledge of the viscous layer thickness, a mesh adaption procedure ca be applied. The Navier-Stokes results produced using adapted meshes are shown to be identical to boundary-layer result , when the computed wall pressure from the Navier-Stokes solution is used as input for the boundary-layer calculation. For the validation of the necessary steps in the coupling procedure, the laminar airfoil DoAL3 was selected. This airfoil was measured in the Transonic Wind Tunnel Braunschweig facility at the DLR, German Aerospace Research Establishment. The limiting N factor for that wind tunnel was determined beforehand.