Navier-Stokes Airfoil Computations with e Transition Prediction Including Transitional Flow Regions

Abstract

The e ow around laminar airfoils is computed using a Navier ‐Stokes method coupled to a transition prediction method based on thee N approach. Applying point transition at the predicted transition location produces a strong viscous/inviscid interaction region that prevents the coupled system from converging, whereas the introduction of transitional e ow regions resolves that problem. The emphasis is not placed on the development of new transitional e ow models but primarily on producing convergence, applying modie ed, available models. A comprehensive computational study is performed in a strong adverse and zero pressure gradient airfoil e ow region, as the transitional lengths differ considerably for the different models. A conventional model, which is applicable in e ow regions wheretransition is predicted well upstream of laminar separation, is proposed, together with a special transitional length model fore owswheretheboundary layerstays laminarup to separation. Thee owsovertheDoAL3 and the NLF(1)-0416 laminar airfoils are investigated. The coupled Navier ‐Stokes and e N methods are shown to produce converged results. Furthermore, the values for lift and drag are in excellent agreement with the free transition measurements.